"So instead, I end up with men who are either a. commitment phobic, b. workaholics, or c. in love with the ex / someone else"
These men are ALL unobtainable, aren't they. They're all focussing their attention elsewhere. You might have found yourself with an addict before, too.
Please, please read "He's scared, she's Scared". It's not a Rules-style book, it's well-written & intelligent. Right up your street!
You are attracted to unobtainable men because you are a CP who prefers to take the passive role... If you meet an unobtainable man, you feel free to chuck yourself into the relationship 100% because it can't possibly work in real life. So you're safe to fall in love as it can't possibly last. A nice, secure, dependable, unbroken man is terifying to you -- there is nobody else to blame if the relationship fails except yourself (you think), so you don't even go there.
Going for the unnobtainable men gives you an excuse for the rel'p to fail. It has a built-in expiry date.
Your ex is probably a more active-role CP. He prolly likes this new girl because she is unobtainable in some way too. Either she's not that keen on him, or moving away, still involved with an ex, unsuitable in some way... Or she just is (or pretends to be) vv hard to get.