You should bring a different chick home every night and bang her in front of the ex. Eventually she'll join in and it's Win for you. But instead, you'll be beating off and crying yourself to sleep every night she's on the phone with the jagoff she dumped you for. Nobody mutually agrees to break up. She moved on, but was still living there, and you got tired of the fact that she was hiding her infidelity from you so well. So she made you feel like it was all good and that you were in control of the situation.