the question of WHY???

I'm acting like a little kid again... Asking the questions WHY...It's funny, but I can't figure the answers, no matter how hard I try. Explain to me- why do people hurt the ones they love so much? It's life people don't like having healthy and peaceful relationships, they just want to agrue over little things. Some even make up some bullshit to fight over. What's wrong with this world? Look at this. I am in the relationship, where I'm completely honest with the person, I tell him everything that's happening in my life, I shared my past with him, I trusted him. Yesterday he claimed I lie to him and that I change things around everytime I tell him something about my past. I don't get it- he doesn't even have to know about my past, it's my life, nothing can be changed, nothing can be forgotten either.So what's wrong?Today he apologizes and almost cries, because he feels like a piece of shit. But the pain from yesterday, the pain he caused...It can't go away so easily. It seems like as if I were a bitch and treated people like shit, they would treat me better. I just don't this this is fair. makes me mad. That's why I wrote this, cuz I just wanted to scream about it...I wonder, if I'm the only person who feels this way...