I need an unbiased opinion on this.

I hooked up with a girl who at first was way more into me than I was into her. I was casual, hooked up with other girls, and didn't respond to a lot of her texts ( I know I'm a jerk- and trust me I'm paying for it) - however after a while she grew on me and I called her hoping to get a little more serious, only to find out she had started seeing someone else.
After we hung up I called again to apologize for not taking her more seriously - she didn't answer but texted that she couldn't talk to me because she was in love with me. I then out of impulse dropped in on her to tell her I felt the same- to which she replied- I can't do anything about that.

I slumped away, and didn't talk with her for about month. She has gotten in touch with me several times since- my feelings for her have only gotten stronger- but I'm all but certain she is still with this guy ( I was thinking it may have been jealousy at first, but I know it's real now) - what should I do? Thanks for your time advice is appreciated.

If she is still with this guy, then you need to take a step back and leave her alone. I know that sounds kind of harsh, but seriously... there's not much more you can do. Maybe, just maybe... things with this other guy aren't that serious and she will give you guys another chance. But... until then, go out and date and have some fun. Try to keep your mind off her. Good luck.

Ah, the star-crossed lovers.. Believe me, this is not an uncommon problem. Been there myself and spent 20 years trying to sort it out, him available when I wasn't and vice-versa.

It's an exciting and memorable situation, and who knows? Maybe one day you'll cross paths when you're both available. At least you know that she is a very honest and loyal woman since, even though she acknowledges that she has some feelings for you ("love" is kind of a strong word for a one-night-stand), is smart enough not to leave one man for another. That never works well.

My recommendation is that you go on about your dating life, learn from the experience not to be quite such a dog, and just let whatever happens happen. You two may wind up getting another chance to actually get to know each other. You may not. And even if you do, you may find that you won't get along over the long haul, so don't let this "possible" ruin you for other "probables" while you bemoan your mistake.

Good luck!

Thank you both for your answers. I think you are both right. Even though it hurts a lot and goes against how I'm feeling I've let her be. She is still commenting on my status updates and whatnot but I've been casual about that stuff, but I don't really understand why she's doing it. I'm not really a ladies man at heart, but I've tended often in my life to play that role. Although it makes me feel like a hero and cool guy in all of my social groups - Its all phony at the end of the day. Even though were not together - this girl made me realize that fact- I can't blame her for not dumping this guy for me - I was acting like jerk - and for all she knows it would have been a terrible decision. The thing that bothers me the most now is that I portrayed to her a version of myself that does not truly reflect who I am. Do you guys think it would be detrimental to any future chances we might have if send her a letter of apology, or would that come off as obsessive? Im not sure how serious this new thing is - she even said - when she told me about him, that she wasn't as into him as she was into me, but that he's a good guy and wanted the same things that she did - in terms of a more serious relationship- she even said she thought she might be settling for easy - I don't know how she feels now, but Im thinking this relationship was built on shaky ground and likely won't go the distance. - maybe I'm hopeful - I have moved on dated a couple more girls but Im not really into them. Anyway - thanks for your help- happy to return the favor when I can