Can a man really change if he has hurt you??
Just a theory OP, but maybe you get burned a lot because your good heart gets in the way of your "F this guy, he's a loser" brain. Do you have a hard time turning away screwed up people because you refuse to accept that there are plenty of your fellow human beings who have little, if any, redeeming value?
I see so many shallow, petty reasons that people exclude others as possible partners it's ridiculous. But there are some who go too far in the other direction and let low-life users move on in and do their thing. The results should not be surprising.
And now to totally confuse the message OP, I will tell you that a woman with a big heart is absolutely magical, beautiful to me. hehe...you just need a hard ass like me in your life to deliver the boot to all the weasels that come around.