I can't hold onto a relation...

Hi,
You are a typical "Hunter".... you like the hunting (the chaising) more han you really want those girls.... All you have to do is decide: Stop hunting and focus on getting the one girl that really means to you..... The minute you do it your entire attitude will change. 
Best regards,

I think it's a matter of maturity. You seem to like the challenge of getting the girl and that's fine but there is something immature with this approach since you aren't necessarily happy with the way things are (you say yourself that you're looking to be with a girl long term). It might be a matter of having enough of this style of life and it might be a matter of maturing from withing but something must change if you want to have a serious relationship.

By the way there might be a psychological reason for your behavior. Getting some professional help might help you get to the bottom of this. 

Hi,

     You do these things possibly because you have a very low self-esteem.  You think it is cool to collect girlfriends, add them to your list

and boast to your friends.  That gives you a temporary high but that does not last because you know deep in your heart that you played with people's emotions and hurt them.

    You need to mature more, the source of your self-esteem should come from doing something productive, something that gives you the

self-pride and if you can honestly tell yourself that you are a worthwhile person, that you don't intend to play games and hurt people's feelings and emotions.  Then at that time you may rise to the level of a DOG, not a PIG anymore.