I'm expecting my gf's 26yo son to start growing up and move out of his basement. He works, pays no rent, and plays video games/drinks all weekend. No household responsibilities and his room is obscenely filthy
What does your girlfriend think? Are you that worried about him?
I am worried about him. Not worried about him as an adult, but worried about him as a human, because he's disgusting
That's between your gf and him. I don't see how this is any of your business.
I'm worried that he's going to be a fat, depressed loser when he's 40. He has no hustle or drive to be good at anything. I want him to eat healthy and stop being so lazy.
You should take this topic up with your girlfriend and allow her to decide how to deal with her son. Until you get married, you can't really have a say in the matter, though you can discuss it with her and try to help her see how her son is not helping himself.