If u saw a man beating a woman, would u call the police ?

Once again I have seen something that many of you don't have the opportunity to see. While I was at a restaurant eating my breakfast this morning, I noticed something. Outside a few feet away, and I saw a man slap a woman. Before you say anything, this couple is seen all over town daily. People saw them fighting from a distance, and nobody did a thing. I started to call the cops, but something said no. This was while I was about to get back into my car. I just stared, and they saw me looking at them. Then I went on my way. She has been with him for a long time, and I am sure her boyfriend has done this before. I thought to myself, why bother, she will just go back to him anyway. Was I wrong in not calling the cops. Something inside of me said this, she will leave when she is tired of him and for good. What do you think ? Give me your answers please. ☺