Why do i keep thinking of my ex. Although its over, we keep contacting each other. And every time, things don't work out.
Every other girl i dated since seems unappealing to me..

From my experience, quarelling is still a good sign. At least there is communication, and it shows that both parties want to work on the relationship. Every good relationship will have its up and downs. The important thing is to avoid making the argument personal and destructive.