
My first thought is Dungeon Siege III. My wife and I played through that and she loved it. Lord of the Rings: War in the North is also a good co-op action RPG. I know you mainly play PC games, so I don't know what consoles you have access to, but I've heard that Tales of Xilia has good co-op (haven't played it though). Uh, Borderlands 2 maybe? My wife liked that one too. Oh, Child of Light! I hear that has co-op. But yeah, mainly Dungeon Siege III