What does "fun" mean for you, right now? I really am curious. There is nothing wrong with having fun. There is nothing wrong with casual sex as long as everyone is safe and honest about what is happening.
But, B, if you are not being honest with yourself about what you really want then yes, you will keep finding yourself repeating the same relationships.
And sometimes your HP really wants you to follow your own heart and isn't sending you signs about what you should do. Try not to put all the decision on him/her/it all the time!!