He should just play with her. He'd get to spend time with her and they'd probably both have fun (since New Leaf has so many multiplayer features) that way.
My husband and I are both gamers though, so my answer is kinda biased. There's some games that one of us will play that the other isn't interested in, but for the most part, we like similar games. It's a lot more fun when we can play the games together.
My boyfriend who lives with me probably feels like that husband. He's seen me play these types of games endlessly and I think he gets a bit jealous. He kept making bets with his friends about how long I could last till I bought the game. I lasted a week. He even laughed at me as I wondered around the Japanese 7/11 with my 3DS open trying to figure out the Japanese and buying groceries. Seriously 3DS in one hand shopping basket in my arm and stylus on my other hand.