Am I falling in love with the wrong people or is something wrong with me?

I have been in three relationships and all have failed. These men are nice to me for the first three months and do everything for me.I dont know what happens suddenly they seem to lose interest in me. They dont leave me and they insist that I be with them. I get smitten by all the love and affection thay they show and try to force myself to be in the relationship. They stop doing all the things they were doing before and when I want to break up they emotionally blackmail me. I pity and then get back to them. At one point, I reach the saturation point and leave them. I dont know why the same thing happened in all the three relationships. I am wondering if there is something wrong in me or with them. Please help me