Jillian, I think bcgirl was sharing her story so you could (perhaps) understand the mindset of someone who behaves the way your ex has been.
You are very naive to think that everyone behaves (or even should behave) with complete honesty in their relationships. You might be interested to know that many cultures would find your viewpoint simplistic, like that of a child. There are many reasons he might not have told you flat out that he isn't interested in you: not wanting to hurt your feelings, not seeing any percentage in telling you (b/c if he's dating others it should be obvious), or yes, b/c he's a selfish jerk. I suspect, tho, the truth is probably somewhere in the middle. You are, based on your posts, most definitely obsessive about this guy. So. Could he have been more honest with you? Sure. Is he required to? No. You are an adult and able to make your own choices about who you expend your energy on. If you made a bad choice about this, well, it seems only you are suffering for it.
We can try to explain his behaviour, but why would we? He's not posting here, you are. And my final advice to you is this: You are going to end up bitter and alone if you don't learn to modulate those expectations of others. People don't owe you any type of behaviour. If you want respect from others you need to take it for yourself. Learn to say clearly what you want and what you don't. Stop expecting others to fill in your gaps for you and you'll be happier for it.
Best,
- Indi
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh