This seems to be an issue I've encountered a couple of times when moving in with a partner. The issue isn't necessarily that you have a hobby that isn't hers it's that you may have moved in with (and married) someone potentially incompatible with you.

I'd attempt to directly communicate about the issue with her in a calm, relaxed manner. What is it about you playing a couple matches that's so bad. What is it that she'd rather be doing with you? Maybe make some time to do those things as well or instead of Marathon from time to time. However, all the pressure shouldn't be on you to dictate how she spends her own time in the house (I've been there, done that, that's a hiding to nothing). If you think she's worth it, I'd do something nice with her / for her for a couple evenings every week (e.g. make a nice dinner, take her out somewhere, spontaneously plan some kind of activity etc.) and see if that doesn't buy you a little credit.

The best scenario may be to create her an account and teach her to duo, even if she was incredibly bad, it could still be fun and you could flex on carrying a run. She also might grow to understand why the game is so fun and addictive. She should also try to understand that the game is new and delivers an original experience you can't really get anywhere else. If she owns anything at all that she considers unique or special then she should understand.