How can I deal with my mother's boyfriend?

Sounds like she IS being fairly selfish. Changing everything around like that, I mean. I think it’s bad enough in my home, where I have to deal with being the eldest. generally in terms that any kind of reprimand I get is on steroids when compared to my siblings, and things that my parents don’t give a second glance at with them, I get picked on constantly for. However, this has been the routine for years now. If they were to suddenly, say, start saying that I can’t be dating anymore, or garbage like that, I would move out. Why? Because they were letting my younger sister drive at 16, after having practically given her the insurance money, while I had to wait till I was 17 to get a freaking permit because my job then wasn’t the best paying(inconsistent hours, you know?). And, well, she’s been “going out” with guys since she was in middle school, and has since then been using her privelages for what I consider less-than-appropriate activities, at least half of which my parents don’t know about. And BRAGS about it to me and my baby sister.

Well, got a bit off track there. No, it’s not right that she’s changing up EVERYTHING like this for her new “love”. If anything, he should be changing for her. It’s generally the male that has to prove himself to the female, not the other away around. That’s called nature. The fact that she’s brought up, “Don’t want me to be happy?” thing is a classic sign(to me) that she’s trying to relive some lost youth. Especially the activities you describe, or more specifically, the lack of discretion they have while performing them. That’s something that I would expect horny teenagers to be doing, not two mature adults. If and when you’re going to be like that, go somewhere where people don’t have to listen to you, like a hotel, or the apartment that’s not occupied by other dwellers. It does bad things to the mind to think of the one who brought you into the world like that. Even worse to realize when they are, or heaven forbid, walk in on her(them).

If you truly are an adult, I would suggest finding somewhere new to live if things can’t be ironed out. She’s obviously more than ready to put her needs of her child’s, and I can’t say whether or not that will change, since I don’t know her personally. Try to talk with her, make her realize how much you love and respect her for being your mother, and that her example and experience is still very important to you. And get across to her that the new guy is unwilling to show you any respect. My girlfriends brother is a bit immature for his age(in my opinion), but I make it my mission to get along with him, and it works out well. And I know that he has no problem with me, because he makes no effort to prevent us from doing so. If the boyfriend isn’t at least willing to suck up enough pride to get along with you, then that already shows some of his motive, whether it be ulterior motives, or the absolute lack thereof.