My boyfriend is confusing me a little...?

okay so my boyfriend and I have been going out for like 5 months, and I'd like to think we're getting pretty serious. the topic of "the future" comes up all the time, whether it's me starting that conversation or him. Like he'll say something like " if we put the money we'll be making together in the next few years can you imagine what kind of house we'd be able to afford?" and very similar sayings about travel, cars, etc. he's even talked about kids, I'm not sure exactly if he wants them but sometimes he seems into it. then the other day we were talking in the car about sex, because I've told him from the get go that I only want one sex partner and it will be to the man I hope to marry. and I basically told him that unless I'm engaged I'm not going to have sex. and he said " well you know I may never want to get married right?" why would he talk about our future all the time and then turn around and say he may never want to get married? I tried to get reasons why and he said its because he doesn't want a huge 500 people wedding, and neither do I (my ideal wedding would be immediate friends and family at a small church and then have some kind of potluck type dinner) so he is confusing me quite a bit