I struggle to see why anyone would do this. My boyfriend recently found out that despite telling his ex to deal with a bill that he had been paying for her during their relationship and to pay for it herself, she didn't bother and just let him keep paying it. For over a year.
Now he is an idiot too for 1. Not even noticing and 2. Not checking she had changed the details, I'm not saying he is innocent here, I told him he was an idiot.
But how can someone actually be OK to do that? What goes through someone's mind to think it's OK to let someone else pay their bills? She apologised, but didn't offer to pay him back. He isn't gonna ask her for the money either as it would mean having to talk to her (his words, not mine). She probably couldn't afford it anyway now as its like over £300 she owes him.
It shouldn't really shock me I guess, not everyone in the world is nice, but it does.