Love really is a strange thing...

Been at a party last night, meet some great people, talked with "lost" friends, had a great time. But what stucked most, was a beautiful girl and her "boyfriend". I noticed her quite soon, when they walked in and sat at a table across mine, she had big green eyes and blondish hair. There were other people sitting there as well, they all knew each other. They were chatting like everyone, then it happen. He hit her. Not just a small slap on the cheek, he cut her lip. The music was too loud for most people to notice anything, their table of course did. They paused for a minute, she took a tissue to stop the blood, then they simply started chatting again. She leaned back into the shadow and then we made eye contact. We look into each others eyes for about a minute, then she looked at the floor. I have a feeling that moment and that look is going to haunt me for a very long time.
I simply can't stop thinking about it. First about the moment when it happened. Should something be done, should the guy be reported/kicked? Or would that just make it worse for her later?
Then about her point of view. Is it love? Can someone that's suppose to love you, do that to you? Is it ok to let that happen to you? How can you "love" or even be with someone that does something like that to you? I don't know, I don't get it, I'm lost..

Couple of minutes later, she engaged in their conversation again, like nothing happened. Somehow I got a feeling, it's not the first time something like this has happened to her..
Greeneyes, go, get away, you deserve someone A LOT better then him! Love is a special thing, don't waste it on someone like that.