First, just ask her if you are still on for Memorial Day. It should provide some clarity as to how she wants to proceed. If her response is along the lines of “Of course!” then you will know you have a shot at keeping the friendship moving forward. If she begs off, you can at least plan something fun to do with your daughter to take the edge off her (and your) disappointment.
Its great that you want to be friends with her, but really, you don’t. You want to be her lover, partner, a whole lot of things that go beyond friends. Your first reaction on seeing her for the first time after she shot you down and after having ten days to organize your feelings? “She looks stunning.” That’s not a guy talking about his good friend; that’s a guy who is smitten.
Everytime you see her looking like a knockout, your penis is going to look up at you pleadingly and say, “Please? Can we? I bet this time she says yes!” And every time you behave yourself (and you will, because you are a decent man), your penis is going to hate you just a little bit more. Why be mean to the little fellow? He’ll be much happier in the long run if you chalk this one up to experience and work on finding someone who wants to be your friend AND your lover.
Think about it. Being just friends with her has the potential to just be ongoing torture. What are you going to do if she starts dating someone else? (If she’s that wonderful, it’s likely going to happen.) Either she’s going to drop you as a friend in all but name, or she’s going to treat you like a girlfriend…either way, you will feel like shit. Let’s see, you said she’s stoic and reserved, so she probably won’t let you know until its gotten pretty serious. She just won’t be available to text or have lunch as often as before. And then it will be: “Drew, I’ve gotten engaged, and we’re having a little party to celebrate, We hope you’ll be able to come!” And of course your big brain will say all the right things about how glad you are for her and how lucky he is, but all the while your penis brain is going to be saying “dammit! dammit! dammit! dammit!”
You say you can’t imagine a future without her friendship, but really, what is your position going to be in her life? “Jim, this is Drew from work. He got divorced about the same time I did, and it was so wonderful just having someone who understood what I was going through! He was so nice!” And Jim will give you a nice firm handshake and flash a winning smile, and say “Hi Drew, Nice to meet you,” and his eyes will say, “Thanks pal, I’ve got it from here.” Christ, why not just stab yourself in the dick and put it out of its misery?
If you do go forward with your hopes of salvaging your friendship, don’t ask her about explicit boundaries. That is just a whole bucket of awkward right there.