My best friend of almost 18 years is not a gamer, and I still adore him. I guess after a point you stop caring about little things about what kind of game you play and worry more about enjoying the people you're with.
My husband and I don't play much of the same games. He likes stuff like Kerball Space Program, the Batman Arkham series, Starcraft, Candy Crush and Wolfenstein (the newest one and it's awesome.) I've always been more of a RPG/JRPG nut; while I've definitely played and beat the crap out of the God of War series, I'm more of a Final Fantasy/BioWare fan. We enjoy playing Diablo 3 together and we used to play MMOs together. However, he's just not into the Dragon Age games. He's not a fan of the playstyle more than anything else.
And you know what? It doesn't matter. He talks about his progress in the new Alien game while I chat about dragons in mine. We're both having fun sharing our love of pixels. That's all that should count.
You and your friend like destroying pixels together. He likes his in the shape of a gun and human enemies; you prefer yours in the shape of a sword/staff/bow and monstrous enemies. Life's too short to fight over what genre you like. As long as you're both having fun, who cares?