Most Helpful Guy
If you are having trouble getting guys to commit its because you are shopping above your league. Guys will normally sleep with girls a few values below them but will rarely commit to them.
Sounds like you left your boyfriend for someone you found more attractive but couldn't keep him around.
Most Helpful Girl
It just depends what you really want. I understand wanting to change because you really like a guy, but at the end of the day, you'll just be unhappy that you don't have what you want. It sounds like you're really looking for a real relationship and this guy can't give that to you, so just accept that he's a good friend and stop trying to change yourself so that you can force something that isn't right.