Does sex bring couples closer together?

Okay, so I’m 28 and my boyfriend is 26. We’ve been dating for three years and have lived together for over two. We have actually never had sex, although we do things other than intercourse. (I know, hard to believe, but it’s true!)
Lately, I’ve been thinking more and more about having sex…I know that he’d be all for it! My main reason for waiting is that I kind of want to be married (or at least engaged) first. It’s not a religious thing for me, just a personal choice. I want to know that our relationship is going to be permanent first. (Please no comments about the possibility of divorce later on)
The problem is, things have been different between us lately. It just seems like something is missing and our relationship is not like it used to be. I’m not looking to sex to make things better. That’s not what this is about. Like I said before…it’s actually something that I’ve been thinking about lately. Considering the fact that I’ve been contemplating it anyway, I guess I’m just wondering if this could possibly help us.
I’m just wondering, does sex bring couples closer?