She can make the demand, and then she can make a choice based on the results/reaction to her demand.
You have every right to say "no", just as she has every right to pack her **** and leave.
But you have to choose your battles and healthy relationships are built around compromises.
Maybe you can just promise to play less, and pay more attention to her and that will be good enough. Or you can just put the game away for a while, give it a rest for a bit and work on your relationship instead.