<human>: Give me the gist of the text in a nutshell

So this girl is 19 and I am 23. I've known her shortly and throughout the time she had a boyfriend. She always talked bad about him and then one day he picked her up and threw her on the ground after an argument. I went to her house to help her deal with the pain and just try to help her through everything.(Trying to be a nice respectable guy and show her there are some out here) 

We build a very close bond over a few weeks because I am there for her and helping her out. So throughout the next 8 weeks she takes a weekly visit to see me as i live 1 hour away.  To my knowledge and going by what she says shes single. We go on dates but and I meet her family and friends. 

Throughout the time she always talks about how her Ex that abused her (Physically, emotionally, mentally) was trying to rekindle the flame. I played it off saying you just need to rid this jerk from your life. They decide to meet up and talk. 

Recently I found out they are hanging out and going to lunch and dinner. So I told her she had to choose me or him because I am not playing love triangle. She decides that she wants to get back with him because he's such a nice guy and that was only one thing he did wrong compared to all the great things he did during their 6 week relationship. (Even though he admittedly cheated on her, sexually assaulted her, abused her) 

The best part is she blocks my number and blocks me from all social media. She cut presumably the best support of her life out of it. 

So reddit, how does this happen? How does a female go back to a guy like this? Even if she didn't end up with me, how can someone go back into an abusive relationship?
<bot>: (19) Female Im talking to was in an abusive relationship where her Ex (20) has cheated, sexually assaulted, and abused her. After trying to help her move on, she gets back with him.