Not Even Sure What I Want

So I'm part of a fairly large friendship group. About four months ago, I slept with one of the members of this group who I share a lot in common with interest-wise. At the time, as I was reeling from a break up, I told him I absolutely didn't want anything long term, which he agreed with. (In part because of my break up, in part because a nasty break up on his part supposedly left him never wanting to date again - which hearing the details I get, in part because I just don't think we're suitable for each other. He's 5 years younger. I'm a professional, he's going back to school after a stint in the military, I might be moving for work, etc. etc.) Most of the friends in the group know (as we haven't really been subtle), but no one makes a big deal about it. Anyway, the sex was good, so it continued. Sometime in the last month or so, I feel like things took a ramp up from "let's hook up once a month when we happen to be in the same place and no one else is there" to the point where we're hanging out a LOT, sleeping over even when there's no sex, and doing other stuff that feels weirdly close to relationship-territory. (Such as going on picnics together, trips, making dinner together, etc. This is especially weird in that we're both - theoretically, anyway - dating other people. I am, not sure whether he is or not.) So that's weird. Beyond that, I'm not sure whether I want a relationship or not (because of the above mentioned reasons, although work is looking more stable now and, eh, although our career paths are different, it's not a biggie to me - also, learning that this friend is one of the kindest, sweetest, and most amazing people I've met isn't helping me feel like he's someone I want to brush aside for some random guy, either.) Part of me wants to have my cake and eat it to (be able to date people who *might* be better fits, while...IDK, having this guy on the side to hold me when I cry, have sex with me, do fun stuff with.) But, of course, the only fair way to do that is to let him do the same...which is fine (I think I can tolerate him finding someone he loves, provided she's cool - I feel like he deserves someone who is perfect for him as he's a great guy, and if someone else is a better fit, sure, it's going to hurt, but I want him to be happy more than much else), but also a bit painful. I also worry that just being with him (to the extent of taking trips, etc.) is making it kind of hard to date other people in a serious way. So part of me kind of wants to bring up that this is seeming more serious than it was, and I'm not sure how to deal with that, but then another part wonders why I'd mess with a situation that seems pretty golden right now. Yargh. (Then a third part thinks that this is all too soon to bring up, anyway. It hasn't been that long. If I give it a year, maybe it'll naturally resolve itself. And if it does, great, if it's not, maybe I bring it up then.) Advice?

Double standards are bad! I guess my concern is that I'm not sure that it's not going to go anywhere. If I was asked a month ago, I would have said, "No." Right now? I'm not so sure. (Which unsettles me.) But yeah, the veneer seems pretty cracked right now. So I probably should have a talk with him and figure out what it is he wants, if anything. (And figure out whether that's what I want, too.) Since I agree that it's not fair to him to string him along.