My [30M] girlfriend [30F] won't cut contact with a guy that has a crush on her

This has been an ongoing thing for about 4 months now (that I know of) when she had initially brought it to my attention. Apparently the guy doesn't even live in the same country - I guess they met in an online game over a year ago and exchanged Facebook with each other and she had/has been helping him with some issues (depression, etc.) but he started to develop feelings for her and expressed them. She has already told him that there is zero possibility of them ever hooking up but he just won't accept it and constantly sends her messages via Facebook. She had been ignoring them for the past few days but I guess she decided to read them and respond today - she ended up telling me all about it and it's just the same old thing (we've already talked about it 1 or 2 times before and she said she would stop.) I even sent him a message offering him help as that is what he needs but he just ignored me. She said she wishes she was stronger and could just delete him but can't - she did tell me she blocked him from messages though. I'm just getting tired of it and I don't think it's healthy for our relationship - I may be wrong so I wanted to get some input from others.

tl;dr: Girlfriend won't stop talking to a guy that has a crush on her over Facebook. Getting tired of hearing about it as the solution is just to block/delete him but she won't do that yet. Thoughts/input?