I think Toxi's suggesting he leave, not give her an ultimatum.
But why?
No couple likes everything 100%
Imagine you had a girlfriend who was perfect for you, except for one thing...she hates video games. She satisfied yoy on every way, but she did not hit your competitive gaming spot.
She thinks they're childish. She just doesn't get it. There's no changing it.
Option one, you end things, even though everything else is amazing. I mean games are really important to you, but will you ever find a girl so perfect again?
Option two, you give up games to make her happy. You start to resent her. You're moody.
Hm, neither of these sound good.
Option three, you have an adult conversation. You agree that sometimes after work instead of coming home, you'll go out and play video games. You don't have to talk about it. It's just something you do on the side, away from the relationship.
And guess what, you're happy you get your games, and she's happy because you're in a good mood.
A relationship doesn't mean you have to do everything together.