Is this normal with bf/gf relationships?

It seems that my feelings in every relationship I get into always turn sour and I always end up feeling anxious and uncertain towards my boyfriend and eventually breaking up after just a couple weeks-months of starting the relationship. These emotions usually develop after making out and minimal light petting (NOT sex) for the first time. I do not understand why I feel this way. It seems that any good, loving feelings are very fleeting and temporary for me and I feel the urge to keep moving on to dating other guys instead of staying in relationships. I was diagnosed with depression/anxiety last year but it is not major or debilitating and I am able to function really well. Could this be symptoms of minor depression or is this just the way I am?? Please help me.