The problem here is that you are the one who moved in with your boyfriend [i]and[/i] his brother. You’ve already agreed and condoned this roommate situation rather than a romantic couple living together. So the scene was set for a frat house lifestyle when you agreed to move in with both your boyfriend and his twin.
Since you’ve already made things very clear to your boyfriend about what you want in terms of your living situation, and he’s not willing to do it, you have to be the one to make the decisions that will govern your life. You can’t press him into something he doesn’t want to do, and clearly, he’s not ready to get married.
If you move out, which I would advise, you should move out with a fresh start in mind. You deserve a guy who’s going to want the same lifestyle you do. You’ve spent way too long committed to this frat house lifestyle. It’s time for you to get what you want in your life. Understand that your current boyfriend doesn’t want the sane thing you do, and that to get what you want, you have to move on. If you don’t, you’re going to get more and more angry at yourself, and take it out on your boyfriend. He’s being clear. Now the ball’s in your court. Make your move. 😉