You may not be in love.
Fear of being hurt and abandonment issues.
There is no way to psychoanalize what causes you to behave a certain way (at least not on a public forum like this) . Like consistently sabotaging your relationships. It is far too complicated. You could be experiencing any number of emotional disabilities triggered by any number of things. Then again, It may not have anything to do with that at all .. It could simply be that the "love" you are being offered is just not right for you. There are a number of factors that makes a true love relationship work..first you have to BOTH feel love for each other, and BOTH be willing to cultivate that spark into a burning flame that can last a lifetime.