Did you dump him? Please tell me you dumped him by now.
I actually met her a few times already, the most recent one was at his friends’s party (since he invited her for lunch earlier that day, and brought her to the party later in the night). There was awkwardness at first but then I appreciated the fact that she was trying to engage in a conversation with me as much as I was with her. I thought that was a good start. And then, a few days later, he started telling me that we hang out too much, that he wants me to start my own social life and a lot more things (He is nice guy and I don’t want to paint any more bad image of him here). I just felt that it was too conflicting to claim that my reaction was a result of culture difference.
He said that he doesn’t care if I would be friends with my ex, but I care.
Seconded
If he is excluding you, its because something you wont like is going on. IF he offers to include you and you decline or don’t mind that he sees this ex-friend alone thats a little different. Flat out forbidding that he have any contact with exes would be unreasonable in my opinion, but regular lunch dates I think is over the line.
I am sorry to hear he said mean and or disparaging things to you, he probably feels like he has the ex back so he can discard you and not worry about it or needs you out of the way so he can get her back …
If the roles were reversed, he would probably be just as upset as you if you were excluding him to be with your ex-bf. If you were my g/f I would at least want the option to tag along. I would also have a very different perception of catching up every 4-6 months over lunch vs. weekly outings.
So, now that its looking like you’re gonna be single 
Makes you cry and forbids you to go on outings with him and his ex? Yeah…Sounds like a completely nice guy.
He explained that his ex (who he claims his best friend) is the only person he can talked to concerning his personal issues from home. And that he can’t talk to me in that level because of reasons that just boils down on well, she has time to listen to him now.
Culture has nothing to do with it. He only brought it up in the first place in an attempt to excuse his behavior. As drach said he’s excluding you because he knows you’ll flip when you see how he behaves with her. And he would care if you were friends with your ex. He just happens to know that you’re not friends with any of your exes (I’m assuming) so it’s not something he’s got to worry about and he knows it’ll never come up. He sounds like an assclown.
He’s full of shit.
If he says he can’t “talk to you on that level,” then he’s saying he can’t relate to you as a serious partner. He’s wasting your time.
He’s not going to get any nicer or more sensitive. This is what he is. If what he is makes you happy, stay with him, if not, leave. Don’t make excuses for him, though, and don’t imagine that he’s going to change. Breaking up isn’t the end of the world. There are guys out there who will want to be your boyfriend. This guy doesn’t.
I guess, I have to make the right choice. I care about him a lot but this relationship clearly does not make both of us happy anymore.
His actions are painting the picture loud and clear.
He’s mis-representing the situation here; I don’t think it’s being friends with his ex that is the problem for you, but the way he’s going about it (excluding you, accusing you of ridiculous things, claiming that what he’s doing is normal in western culture, etc.).
In other words, you’re just a placeholder because the woman he really wanted didn’t want him? No, he’s not a nice guy. Not a nice guy at all.
Sweetie, please, get out. You deserve so much better. Kick his loser ass to the curb.
hugs Good luck.
This is a key point for me. I don’t have a problem with someone remaining friends with an ex, or someone else of the opposite gender, but if he is OK with that, then why didn’t he remain friends with you before? It was OK for her to give an ultimatum, but not for you to give the same ultimatum? He is 100% wrong in how he is handling this situation.
I am actually friends with my exes. In fact, in the past, one of my exes cheated on me, instead of bitching about it since it already happened, I talked to the girl and thanked her for treating him well. I mean, what do I got to do?
You walk away from people who hurt you, that’s what you do. It may be a good thing to be polite to people who do not respect you or your feelings, but it is not a good thing to allow them to have the opportunity to treat you cruelly.
I don’t really mind if that is what’s going to be. Reality bites but eventually things will work out well in the end. To all the single ladies, put your hands up. 
Who was it said that nobody can make you feel inferior without your permission?
It’s time to ditch him for real now. You seem nice, polite, understanding and reasonably open-minded, but he treats you very badly. You’re too good for him, seriously, he doesn’t deserve you. He is still in love with his ex and he is using you and your niceness.
To be honest I’d guess that, in his exclusion of you from social interactions with them, he is either trying to build up jealousy in his ex by telling her positive things about you/the relationship or trying to elicit sympathy from her by telling her nasty things about you/the relationship. Either way it’s part of a plan to win his ex back and he doesn’t want you to mess up the picture of you he has painted for her.
You should leave him. You deserve much better.
I think you know what I’m going to say. It’s been said many times before in this thread, and probably a lot more eloquently.
He’s up to something with his ex. He wants her back, or they are becoming fuck buddies. Either way, he’s not in this relationship with his whole heart.
The most diagnostic behavior of his was not including you in their social engagements. There is really no reason for that other than they were talking about things he didn’t want you to hear. Or, they were meeting for sex. Or both. Either way, it was not innocent.
But, as hard as it may be to do, try to see the bright side in all of this. Before you made major life decisions together–buying a house or having kids, to name a couple–you found out that he was a manipulative and hurtful person. His jerkish behavior has given you a gift, really–a perfectly valid, objective reason for ending the relationship. You’ll never look back on this guy and pine for him as the one that got away. You’ll know that he was a dead-end.
Best wishes to you.
Divisible, Asia is a big country. Where are your from and how long have you been in the US? Depending on the answer some of us might have more insights for you.
Elanor Roosevelt.
OP–Don’t put your wishbone where your backbone should be.