BFS faking a relationship with a friend...

My boyfriend (of 6 years) met this online friend this year... She has a crazy stalker ex who does whatever he can to get in contact with her... he'll make new accounts to message her and everything. The thing with her is, she wont ignore him. She cant just delete the messages and move on...

My bf and her decided to fake a relationship to try to get her ex to leave her alone. It's been going on for a few weeks, but I didnt know about it myself until 2 weeks ago, when I noticed he was chatting on fb with someone nicknamed 'my baby'...

I know this is a fake relationship, cuz this crazy ex of hers has been messaging my bf complaining and trying to get in contact with her... BUT it still rly fucking bothers me that hes doing this. Fake or not, its disrespectful. To even talk to another person the way he is 'fake' talking to this chick... its just not okay. Right?

I've brought these concerns to my bf, and he says hes just helping her... theres no other way to stop this crazy ex... as if a restraining order or something wont work better? Like my bf and this girl arent even friends. So why does he feel like it's his job to help her?

Any advice?