I'm very young and single, but I've seen a lot around me.
The question is do you plan to marry her. Paradoxically, the girl that you are seriously thinking of marrying, is the one that you shouldn't adjust to too much while dating. You will do plenty of adjusting once you are married. I've also heard that the US has a ridiculous divorce rate, probably because they are so individualistic and have unrealistic expectations for spouses in general.
If you're spending like 5 hours a week, then yeah, she needs to accept that true gamers don't play games to kill time, but make time to play games. But more than 10 hours a week and it becomes very detrimental to your life.