Sometimes it feels like something you can't help. If one person you cared about and thought wouldn't hurt you, what is going to stop the next? It may not be the right way to think, but no one wants to get 'burned' again.

Because of being afriad of it happen all over again! Maybe

I don't know...I agree with Sml71...were afraid it will happen again. We are emotional creatures who sometimes have a hard time letting go of our emotions and getting past the hurt and angry of those who have done us wrong.

i agree with the other posts. you're afraid of getting hurt all over again and when that happens enough, you end up carrying baggage to the next relationship, even though u don't mean to. i'm not saying it's right or healthy but it can be hard to let go of. easier said than done for some of us.

It's human nature. We don't live in a bubble. Everything that has happened in our past affects what we do now, whether we are happy with our past or hell bent on not repeating it. However, when it comes to relationships, we have to be careful to not make someone else "pay" for something a past boyfriend or spouse did. In my case, my ex-husband cheated. Yes, I am paranoid that it will happen again. BUT unless my fiance now shows symptoms of cheating or gives me some reason not to trust him, I can't hold him accountable for what someone else did to me. Don't get me wrong, I am far more cautious and aware (hence my past has affected what I have with him), but I choose to trust him unless he proves me wrong (hence, not making him "pay" for what past men did to me).

Because history repeats itself. If you don't learn lessons from mistakes of the past, you're bound to repeat them.

Based on experience, I think it's because women put up a defense system to stop history from repeating itself and she wants to ensure or control her relationship so future partners won't hurt her again.
When I was sixteen, this guy had made me do things that went against the very core of who I was, I had lost my morals, my values, and who I was just to stay with him. After he flaunted this new girl and so-called "Love" in my face, I had felt as though I lost myself in being with him; I had truly lost my soul.
When my brother came and gave me a pep-talk, I woke up and became more conscious of how to become more careful of who I wanted to be with. I had expectations for our relationship and never discussed them with this guy which led to our downfall. After we broke up, there was something in me saying, "Get them before they get you. Whatever they do to you, do it back to them." So, I did that for a few months with different guys because I wasn't taking it seriously.
When I met my husband, he saw what I was telling myself, and he wasn't having it. He had expectations for our relationship and he was more about taking us seriously. This is what made me want to be with my husband because he was the first and only man in my life to tell me, "WAKE UP & GROW!" And that is exactly what I did.