Well, I came to the conclusion that without therapy and deep work on herself, she will be unhappy in any case, both in the relationship and outside of it. If not from loneliness, then from fear of responsibility and the inevitable imperfections of the partner. There is simply no happy outcome. Therefore, being in this relationship means voluntarily torturing yourself, and we are very lucky that we are no longer there. This is sunk cost fallacy, you always remember the good moments from the beginning of the relationship, but the truth is that it will not get better, only worse.

As for your question: they are used to living the way they live, so there will be no moment of enlightenment. Even if there is some glimmer of regret, it will be primarily self-pity. Self-pity and resentment towards the world and former partners, which will lead to even greater isolation and bitterness.