I think it was when the pain of being in a relationship was greater than the pain of living alone. That took some doing since I have abandonment issues and had a hard time being by myself. For me it was when my spouse at the time would sabotage the marriage counseling and cheated on me when he was away from me. There were other things too but the fact that he didn't care about me--all he cared about from me was that I didn't ruin his reputation--really struck the deal for me.