Wait, why not play Diablo on PS3? I don't understand what you wrote.
Same screen co-op would be quite a different experience and it helps that it's a game she already likes.
Portal 2 is on my list of games I want to play co-op with my GF. I've never played it.
Should say due to. They won't be updating it on the PS3. And most likely would get her the pc version since I own it on PC.