I know most of you will probably say it doesn't revolve around sex. I think you're full of shit. Maybe you've convinced your girlfriend or wife of otherwise, but I think you're a liar. And to all you ladies out there who think otherwise, it's wishful thinking.

We're masters of the sweet talk.
I know most of you wouldn't be with your girlfriend / wife unless they put out. I certainly wouldn't be with my girlfriend if she didn't. And I also wouldn't be with her if the sex sucked, or only wanted to put out a few days a week, etc. And she knows being with me is pretty much contingent on sex.
So, I'd say that's a pretty fair argument that relationships ultimately revolve around sex.