I wouldn't say I'm all that social or extroverted. When I was littler, I didn't believe that anyone would be able to fall in love with or even spend copious amounts of time with me. I half planned on having a kid with some consenting female when I was thirty-ish, and going off into the mountains and or desert and raising it on my own. I didn't have a hint of need for anyone else. Then, somehow, I got addicted to my first relationship, and my second. I don't quite understand it. It, to me, is somewhat akin to a feeling of safety... some one person who will watch your back, and protect you over all others... and for whom you'll do the same... someone to turn to when times are rough, and someone to comfort as well. And while I'm at it, if there's going to be this female running around with me, I'm going to want sex as well.
A lot of what keeps a relationship goign at first is novelty. Of course this varies on the couple, but for a while anything and everything together is fun. Then, something changes.... something's missing... I dunno... remember, I'm guessing here. Speculating. :) What you have to hope for (if you're going to hope) is that this is simply part of a cycle... like the seasons. You have to start living your own lives again, without loising your relationship. To me this means having a lot of trust and faith (and optimism). Believing that just because the other person doesn't want to be with you *now* doesn't mean that they're going to want to spend even less time with you later. And after some time, they'll likely seek you out again. If they dont, then it really wasn't "meant to be" at the least. Maybe it can be forced... but from what I've seen trying to force interaction just makes things worse.
Now there's something I really had forgotten to consider -- interdependance, that is. This is going to take a lot more thought. :) [silly me] So where, then, is the line that I should be comfortable with between codep and indep? The part of me that keeps getting hurt says that fully independant is the only way to go, with occasional interactions. But that's not a relationship. Or at least not the sort of relationship that the rest of me wants.
I don't approve of 'playing the field' and then breaking up once youv'e found a replacement. If you're not happy with your parnter or relationship to the point of considering other people, then that should simply be the end of it. And if you want your relationship to continue, this specific one, as opposed to just a relationship in general, then you should stick with it as best you can -- not looking for escape routes.