Hey Eq. Sorry to hear you're having trouble, man. Anyway, I dunno if my advice is useful, or even particularly welcome, but in case you find it helpful at all, here it is:
All of us here know you as a very intelligent and very emotional person; I'm guessing you'd probably agree on both counts. Because you're intelligent, I have no doubt that you know how dangerous this entire situation must sound to someone on the outside. But because you're emotional as well, I realize it may not do much good to say so.
Twice in my (admittedly short) adult life, I've found myself in a situation like yours in that I was trying to make someone who had interest in me want me more. I even wondered, just as you're wondering now, whether or not I should drop all contact and let them come to me. I know now, however, that once someone finds themselves asking that question, the relationship is probably already lost. The "should I play it cool?" question only comes up when the relationship is failing to develop properly on its own. I think it's usually an act of desperation, and I say that more as a critique of my behavior than yours.
Also, I think that anyone who is willing to leave a long-term relationship on your account is surely going to be willing to leave you the next time someone new (and therefore exciting) comes along.
And as harsh as this may sound (and I don't mean for it to), you've described yourself as being hopelessly in love with several girls over the course of just a couple of years, and each time, you explained, vividly and convincingly, that you simply could not see yourself getting over said girl. But obviously, in the past, you have. So while it's hard to see past the situation you're in now, but I think you'll probably get past this one, too,
A friend of mine had a girlfriend awhile back who was determined to move their relationship along at warp speed. When they eventually broke up (after several years), she rushed headlong into another relationship. And then again. Each time, within weeks, she was adorning her MySpace profile with declarations of love. Words like "eternity" and talk of her unending happiness and dedication took months, rather than years, to appear. It was like wanting to construct the world's tallest building in record time and not caring where it was built or what the foundation was made of.
I'm not a pyschologist, but I don't think this is all explained by the fact that she, like some people, simply fell in love very easily. I think it stems from a failure to distinguish between love, and being in love, and a need to duplicate the steadidness of the genuine long-term relationship that she'd lost. I don't think you can artificially speed up that sort of affection, though. If you do, it seems to me that you end up giving yourself over to someone who does not realize you're doing so, does not appreciate the fact that you're doing so, doesn't feel as intensely towards you as you do them, or who may simply not be the person you think they are. You have to know and see someone for a long time, I think, before you can give them that kind of influence over you.
I wish you nothing but the best. In the past, I've had numerous people, whose judgement I trusted entirely, warn me about things like this. And even when everything they said aligned perfectly with the suspicions I already had, I couldn't bring myself to listen to them. I had to learn the hard way. And I did. I hope you can avoid that, at least in this instance, but if not, well, I certainly won't be judging you.
Best of luck, man. I hope this helped in some small way.