"Because I love you"

I had a friend who was in a great relationship, or so she thought. They would go out to the movies, make dinner together and sometimes he would even buy her a present "just because". She was still a virgin, he was not. One day he decided that it was her turn to lose her virginity and when she said no, he hit her. This became a habit. She was late for a date, he hit her. She failed a test, he hit her. She went out with her girlfriends without him knowing, he hit her. Thankfully she told me what had been happening a few months after it started and we decided that it would be best for her to leave him. She didn't want to do it in person because she feared for her safety around  him, especially when she made him angry. I handed her the phone and she dialed his number. The second she told him it was over he demanded to know where she was, she refused to tell him and asked why he wanted to know. He replied "because I love you". She told him that she was sorry and that this couldn't keep happening and hung up. I'm relieved that she got out of it before it got worse, but I know that there are a lot of people who don't. I don't understand how you could physically or emotionally harm someone, on purpose, that you claim to love. I wish she had reported him, I would if it was my place to do so. An abusive relationship isn't much of a relationship at all.