Once upon a time, I knew an older couple who did just that. They had gotten married when they were very young, and both had razor-sharp tempers that life hadn’t dulled yet. They loved each other in theory, but couldn’t get things to work out because they both had to be “right” in arguments.
So they split, and as was sometimes the case back in that time, she took the girl child, and he took the boy child to raise, with visitation all worked out etc.
They both remarried, and ten years pass by.
Then his new wife divorces him, and he solders on. At the same time, her new husband dies of cancer.
The two of them met again when he brought the boy child, now mostly grown, to the funeral to support his mother. In their mutual grief, the once-couple leaned on each other, and realized they still loved each other — except now they had the wisdom of a few years and other relationships in between to help them gain perspective on what they had done wrong the first time.
So, ten years after they split, they got remarried again — and lived happily with each other until they both passed.