You were the abused partner in an abusive relationship with the women being the perpetrator. Your scenario ended with your abuser convincing you to stay. This scenario is clearly the one where the person being cheated on is breaking it off. Just because there was cheating involved in your story and a sit down in your story does not make your experience anywhere near analogous with what is going on in the picture.

You don't know him, you don't know her. For all you know if she did what you said and just broke it off she'd get a torrent of "babe come back I'll never do it again it was only one time babe please ur my love" messages for months. Your scenario ended with the abuser convincing you to stay. This is clearly the one being cheated on breaking it off

You are projecting a very unlikely scenario due to your own experiences. The most likely scenario here is that she caught him cheating and didn't want to leave him room to deny so she printed the proof for when she confronted him.