How is a mere man going to love you if you don't love yourself? If you're constantly telling yourself and those around you that you're fat, ugly and pathetic, you'll end up believing it and those around you will soon leave you to your self-pity.
Somehow you've convinced yourself you don't deserve either to be happy or to get attention from the opposite sex. If a guy pities you enough to go out with you, you find you'll put up with anything from him just to hang onto him.
Stop playing the victim: people will take advantage of you and hurt you. You have just as much right to be happy as anyone else, so stop making yourself miserable for no reason!