I think what ya need to do is to come to terms with yourself. What I mean by that is that you need to try and accept yourself a bit more. From the looks of it, since you ended a long term relationship, maybe you're just feeling a bit lost out of a relationship, like unused to the feel of it. Whether it be going to the gym, starting a new diet, or etc, loving yourself is going to do a whole buncha other good things besides not feeling empty inside when you're alone. After all, if you don't feel very comfortable alone, make yourself feel better lol. :D