Tell them to shut up and keep eating!
I don’t know that you have to try. It could be that your daughter was just getting those feelings out in the open and now that she’s done so, she’ll be okay, or on her way to okay.
She said she likes your girlfriend, and maybe she’s feeling a little bit guilty about that. It might be confusing to her, that she likes someone who’s “taking her mother’s place”. She wants you to be happy but she misses her mom.
That said, I’d skip the Alaska cruise for now, even if there were good reasons for not going before. And ditto on getting new cookware. It’s an easy fix.
Your wife was a separate person from you. You were joined in marriage, yes, but death did do you apart. To children - of any actual age - this is a bizarre and threatening concept. The fact that parents were individuals before, during and - especially - after marriage. Most children expect their parents’ widow or widover to remain solitary, because to them, the one has always been part of a pair, a matching set. They’ve spent 25 or so years living and breathing this delusion and it will take a significant amount of time for them to shift gears on this.
And, frankly, it usually ends up getting ugly. Advice? Spread your wife’s things and mementoes around to her family and friends, avoid any other “competing” associations and don’t pressure them into relating to your new girlfriend. Also, never, ever, ever call her “your new mother.”
If you can, try to have a chat with them about what they expect from you, her and themselves. Do they actually come right out and say that they expect you to live out your life in solitary existence until you die? If so, they are shameless and can’t be dealt with. If that’s their point, even if they won’t come out and say it, gently lead them to the conclusion that while what you and your wife had was precious and unique and loving, it was also ended.
Unless they start bringing religion into it. In which case you roundhouse kick them in the nuts and tell them to suck it up.
Talk with your daughter and son. If you can, try to see if there’s something deeper. I could just be the cookware, but it could also be the feelings of sadness and loss that come up when your daughter remembers what your mom used to do.
Don’t leave your son out, either. See if he’s willing to talk. He might not actually feel the same as your daughter, and she’s just wanting it interpret it that way. On the other hand, he may have his own issues he’s trying to deal with.
Read some books and maybe talk with a therapist. Neither you nor your children have gone through the experience of losing and potentially replacing part of the family, but many families have gone through it. We have some knowledge of what comes up. Why not learn something about it?
If I were your son in this situation, I would want to hear that you haven’t forgotten my mom and you won’t forget me just because you have someone new in your life. Remind your son that you, your late wife, your son, and your daughter are a family and nothing will replace it. Your GF will (you hope) over time become an additional part of that family.
Maybe buying new cookware will help deal with most of the problem. You could ask your daughter if she wants the old cookware, which she can either use or give to her own children some day.
Keep the lines of communication open. Reach out to them, even if they’re not reaching out to you.
You can’t do anything about feelings. You’ll feel them whether you want to or not. You can do something about actions, though. It’s up to you. If it doesn’t make much of an issue in your life, it’s just something you have to deal with. If you live in the same house with the woman, well, that’s another story.
There was a time in history when what your grandfather did would have been quite common. Spouses died in childbirth or succumbed to disease, men depended on their wives to help deal with the chores/run the business/take care of the children, and women were unfortunately nothing without a husband. People had to remarry quickly, regardless of their age.
IMHO, both sides owe it to each other to try to make the darn thing work, overcoming the feelings that are bound to come up. It’s the feelings you don’t talk about and don’t accept in yourself that grow in power.
Wow. I haven’t thought much about the memories of my father fading over the years. When he died, I was hit hard by the loss, but somehow I concluded in my mind that I was exactly like him, mostly, and that my life would keep his memory alive. But you’ve made me think that perhaps this isn’t enough.
I would never have thought of that! Just for kicks, I thought of some reasons:[ul]
[li]He didn’t have the money to do it until recently.[/li][li]His wife wasn’t a traveler, or she got seasick.[/li][li]Neither he nor his wife ever thought of an Alaskan cruise. His GF has thought of it, or even done it.[/li][li]He and his late wife did a lot of traveling, but they just never did a cruise. His GF has done cruises.[/li][/ul]
Some people love cruises. I don’t see the point of one, if the boat doesn’t stop from time to time so you can do scuba diving off it.
you don’t, because you can’t. your daughter is an adult now, and she can start acting as such anytime she pleases.
Why don’t you just ask your daughter what she wants (short of getting rid of the gf)?
It sounds like you’re replacing her mother and doing things with her you never did with her mother. (To her. Not to us.)
I’m sure your daughter sees it as a 'midlife crisis meets widower". 
It may have been said in this thread already, and I apologize for not reading through every post (I tried). But, children often imagine the love of their parents as eternal. The idea that you could love someone else again, might be threatening to them in their current relationships, or their pursuit there of.
Either way, talk to them, love them (as always), but above all don’t give up the new love because of them. In reality, the BEST lesson you can teach them is that it is possible to love again.
Talk to them and be kind, but coddling these feelings is ultimately going to be enabling them. Give the cookware to your daughter and tell her (politely) that she needs to grow up.
[quote=“633squadron, post:27, topic:584345”]
[li]Neither he nor his wife ever thought of an Alaskan cruise. His GF has thought of it, or even done it.[/li][/QUOTE]
The whole point of the question is specifically because the OP noted that his late wife had always wanted to go on an Alaskan cruise.
I’m also curious about this, but I suspect it’s probably just a factor of never having had the resources (perhaps money, but even more likely just the free time) before.
For what its worth:
My parents divorced when I was 17. Dad moved out but Mom stayed at the same house for a while (I was living there too). She soon started bringing over another man, which I didn’t like AT ALL. It felt like an occupation by a foreign army or something. It really is a horrible thing to see another man sitting in your dad’s chair, watching the family tv, etc. It’s not wrong, but I think there is a basic psychological instinct against it.
Mom sold the house shortly after that and her and her new husband bought a house together. They didn’t have to, it was just for their own psychological reasons. Our relationship was suddenly much better. I didn’t have a problem with the new guy after that.
We attach a lot of memories to places and things. When a new element is added into the mix of those memories there can be volatility. I’d imagine with a traumatic event such as losing a mom those feelings can be heightened even more.
Now, I wouldn’t expect you to buy a new house, though I suppose new cookware couldn’t hurt. I think you need to find ways of building new memories with your new GF and kids that doesn’t involve elements of the past. Go to different places, etc. And definitely talk with your kids. Make it clear that you need to live your own life, too.
Just flip a coin. The winning side keeps your love and affection, the losing side winds up abandoned on an ice floe in the Arctic Ocean. It’s pretty simple, really.
I hate to sound harsh but your children need to grow up. If they were 13 and 14, this type of thing might be understandable but they’re supposed to be adults. They should be mature enough to realize that a new love in your life doesn’t diminish any other relationship you had or have and they should be supporting you, not making you’re life more difficult.
Communication is the key. Did you feel a lose when your kids left home or married? Life will always bring situations that are uncomfortable at first. And, your son needs to speak for himself. I would tell them how much you love them, how much their mother loved them and how pleased you are that you made a good enough choice in a partner that they can still feel that way about their mother. Share with them that your weren’t sure about them leaving you either but over time you knew it was a normal step to a good life for all of you. Let them know that you value their opinion and appreciate them looking out for you. And, find a way to not keep the relationships separate. Surely there is something that they have in common. You can be their dad and her partner by finding little subtle ways to encourage a good relationship between them without them feeling forced to accept something. It’s not about the problems, it’s about the solutions. I’m sure that your daughter would prefer to see someone new in her mom’s kitchen than to watch you waste away wishing their mom was still here. Sometimes you just have to find the courage to love your family in spite of the difficulty you have in the beginning. Let them know that none of you would have chosen this or you would have divorced their mother. They are old enough to realize that if you are able to find someone that makes you happy you’re very lucky and shouldn’t just throw it away. Make sure your girlfriend understands what’s going on and integrate. The wobble will eventually go away. Maybe all of you should redo the kitchen together. You know, paint it, make it new, involve them. This too shall pass.
My mom died when I was 23. My dad started dating after a suitable interval, and married a couple of years later. I don’t like his new wife. But you know what? Too fucking bad. It’s not about me. It’s about his happiness, and about his making the best of the years he has left. I was mature enought to realize that. Your children need to come to the same realization.
Okay, that’s not advice. I’m not sure I have advice. But what, realistically, do the kids want you to do? Preserve the house as a shrine to their mother? Not let you move on? They are putting their own need to continue mourning indefinitely before your very real need to continue living.
My grandfather died when my grandmother was in her early 70s - and she lived another ten years. She was still a pretty good looking woman and pretty active when he passed on - and he’d been in a nursing home for a long time, so she’d had a chance to let go. I mentioned to my mother that she might find someone else. I got a shocked look as well - but not over Grandma dating - “Your grandmother?, no! She’ll be visiting the damn grave every day and playing the martyr.” And that was what she did. Ten years of “when your father was alive” and “your father was such a wonderful man.”
Anyway, listen to your kids, let them know that no one can replace their mother. But that its possible for someone to share the place she was.
The big question is what your daughter actually wants you to do. If she’s saying ‘This upsets me and I want you to dump your girlfriend,’ then she needs to grow up. But if she’s saying, ‘This upsets me and I want you to understand that as I work through it,’ then I can’t see anything immature there. You’re her father; you share the loss of her mother, and it’s something that you’ll all be living with forever. If your daughter wants to talk to you about her mixed feelings about this next step in the process, and if she’s hoping that talking it through with you will help her move forward, that sounds like a pretty good thing to me.
From what you say, it sounds like how you make her happy is by listening, letting her know you understand, and helping her to understand how you feel and how the moving-on process doesn’t mean you love her, her brother or their mother any less.
Thank you all for the thoughtful responses! I don’t think I’ve ever started such a popular thread! 
Two quick points, before I ponder how to proceed:
I agree (I think with Qagdop) that the cookware is just a symptom. There was nothing special about the cookware – but when NGF uses it to feed me and my daughter, she is Taking the Place of Mom.
My Late Wife (LW) and I went on our first cruise for our 25th anniversary. We would’ve done Alaska then, but because of her job it was more convenient to cruise at spring break-time rather than summer, and you can’t cruise to Alaska in April. So we took Mexican and Caribbean cruises for the next 3 years, until her demise.
I think the best thing I could do for my daughter (other than in general listening to her and hearing her issues) is to suggest that she go to the same grief workshop that I went to soon after LW’s death. I found it very helpful.
thanks again.