What Might Have Been
Leaving a relationship is generally a time when people experience many different emotions. Some of them may be angry, others could be sad or depressed, and some could feel relief due to the fact they believe they have made the right decision. No matter what they feel at the time, learning new facts about the event that caused the end of their time together could make them have new thoughts. What might have been is often what people think of when they learn a situation was not what they thought, but they must also face the fact they walked out on their partner.
There are times when circumstances point to a person cheating on their partner, and it can destroy them as a couple. The person who feels wronged might walk out without listening to a word their partner tried to say, and they could regret it when they learn no affair ever happened. They might be in a new relationship that is not as good, and they dream about what might have happened if they had only listened to their former partner.
Some people watch a partner walking out on them without saying a word to justify their behaviour, but they know they have done nothing wrong. They could see in later years that repairing the relationship would have only taken them making an attempt at explaining the circumstances, but they know it is their own fault for failing to do that at the time. They could have a successful life with someone else now, but it may not keep them from wondering how good they life would have been with that other person.
Regret for the wrongs done in past relationships is something people often find years later, yet their emotions at the time seemed reasonable. Walking away from what had been a good relationship without ever trying to straighten out a big issue could be a regret they will just have to continue living with for the rest of their lives.