<human>: Can you condense the text into a few key points?

First know that I am ashamed to be asking this on an internet [f]orum at 23. I just found [this]  on youtube and got all choked up about it. I don't even *like* Snow Patrol. This is clearly a cry for help.

For the past 3 or 4 months I've been struggling with indecision about where I want my relationship to go. We're amazingly compatible. We love each other and we're good to each other. He wants to move us forward but I just can't get over this nebulous anxiety about locking myself into one path for life and potentially missing out on what could have been. There is a very real part of me that feels like I need to break up, move across the country and experiment more before settling down. 

I see people here advising a lot of posters that their SO has "checked out" of the relationship already—is this what that means? I'm afraid that I've pretty much doomed us by even entertaining these thoughts. I still enjoy our time together, he still feels like my favourite person in the world, we still talk and have sex and it's mostly awesome. We still butt heads over stupid crap sometimes. 

It's not like I'm faking anything. It's hard to even pinpoint what's changed (pretty sure it's just me) but I *think* I feel marginally different about him...not in magnitude, but in quality. I look at him sometimes and it's like I'm seeing a friend more than a romantic partner. Part of me is convinced that's pretty natural after 3 years, but it still freaks me out.

All this angst and ambivalence seems to be coming to a head. I am not a sentimental person, RA. I'm unpleasantly practical and grounded—ask anyone. I don't like what this is doing to me. I'm ruminating like all get-out and it's only made me more frustrated with myself and more confused. I've never ended a relationship this significant before and I am fucking terrified of the possibility. I can't figure out if the onion-eyes at anything break-up related means I'm ready to end it or extremely *not* ready.
<bot>: I just want someone to slap me and tell me this is all some weird hormonal thing and I'm not really immature enough to consider ending something this good because I want to sleep around.