I don't know how to have a relationship.

The number of years of being able to maintain a relationship doesn't necessarily have to do with your likeability. I mean look at all these abusers being in life-long marriages... There are many circumstances that lead to a break up. However I understand that by criticizing yourself now might be your first step to identifying a problem and finding a solution to it. Just remember you need to be kind to yourself too and look at those situations objectively.