I have a relative who demanded her boyfriend marry her. She hadn't worked the whole time they had been together, so he had been supporting her for the past decade and had a couple kids with her. She wanted him to demonstrate his commitment so gave him a deadline to propose by.

The deadline went by so she took off to be with some guy she had secretly met with online. They had a few weeks of hotel rendezvouses and she was planning to move in with him, but not marry him. That way she could squeeze spousal support out of her boyfriend (common-law) for X many years, and then she and this new guy would marry.

Boyfriend bent over backwards to get her to come back but she wouldn't have any of it. Then she caught the new guy cheating on her and she graciously granted her boyfriend another chance, so long as he would move to a better house.

He only found out after she'd moved back in and sold their house that she had been with that guy during their break.

People can be this horrible.