This is a fascinating thread as it seems remarkably similar to the situation I'm in.
With us, things have come to a head for me because we are talking of moving house, to something much bigger and more expensive. As we are, we could afford to run 2 households, but were we to move, I feel I would be committing myself to staying with dh long term.
Most of the time things are fine. We are definitely not 'in love' with each other any more. dh can be an absolute shit to me sometimes, but can be kind and thoughtful too.
Sometimes I feel I try to over-analyse things and that if I'm not always completely miserable, then there's no point changing things. The grass is always greener, better the devil you know kind of thoughts.
When do issues between a couple become insurmountable? How much do the children really pick up? dh is rarely here anyway, doesn't see them from Mondat to Friday and plays very little part in the practicalities of their upbringing. Is it so awful to live together, even if their image of a father is not ideal. What would change by splitting up? Then they would really see his selfishness. At least at the moment I feel I can shelter them a bit from him. It would be more difficult if we lived apart and they would be supposed to go and stay with him. That would frankly terrify me as he has a terrible temper, is totally unaware of children's needs and safety.
I don't know what the answer is, but we muddle along. I'm often unhappy but really not sure if leaving could be the right thing to do. But I don't want to move as that would take the option away from me. I sympathise.