This isn't simple videogame addiction, this is depression. I'd know, I've been there (though streaming wasn't a thing then), I displayed similar behavior when I was around 19/20, I'd use games as a scapegoat because I wasn't happy with life but I wasn't addicted TO games, I was addicted to avoiding life. I'd miss college classes to stay at home playing because my online friends were more fun to hang out with than my irl friends, I'd put my phone on silence and forget it somewhere, to the point where my grandma called the cops to check up on me because I wouldn't pick up the phone. I wouldn't know if it was raining or sunny unless I had to go outside to buy food/cigarettes, suicide would cross my mind every couple of days.

I got out of it because I had people who cared. This is not to say that OP should stay with him or help him out of it, but from the behavior described it seems like the main concern should be why he is addicted to games and not so much that he is. OP already said this is not a battle she wants to be in, so I guess he'll just have to rely on somebody else do does.