Thanks for the clarification. After discussing this with my wife, we decided in "friendly" games between us, we'll randomly draw and discard character cards. This way, no one (read: my wife) feels "ganged up" on or deliberately screwed by the other player.
This is fine, as it will allow for repeated plays. That is obviously what I want. We can always revert to the intended rules when we play multi-player.
Alternatively, you could play the intended rules in your two player games, but just don't give her the opportunity to feel "ganged up" on. Play that way until the third time she feels she could/should/does gang up on you. Give her the chance to figure the game out to the point where she sees the advantage to "ganging up". That way, when you do finally gang up on her (and be the second person to do it in that particular game) she will appreciate it more.
Same number of plays, and more of a fun end result.