Not long ago, an acquaintance of mine ended a ten year relationship. The union was toxic and unhealthy and she had been exhibiting co-dependent behaviors for some time. She took on all of the responsibility, while he contributed almost nothing emotionally and financially. So after much thought, she decided to end it.
The break up was a long time coming, but what shocked me was that within a week, both of them were involved with other people. Infidelity was not the cause of the break up, but they were both behaving like being single was a disease and they needed a cure fast.