Time and resources seem to be a large factor in whether couples are prepared to overcome unsatisfactory behaviour.
Finding oneself and starting again can be a privilege of the middle class and upwards.
But overall the forties age group tend to be where couples seem to diverge and become competetive, is one better than the other, they if not very loyal in nature, begin the one upmanship dance and stop working together as a team.
It takes a very mature couple to understand (if there is no abuse) that relationships ebb and flow in virtually every way.
I've known many people destroy, perfectly decent partnerships in a race to become the winner in these situations and known many regret their reactionary behaviour to be seen as top dog, quite often going from the frying pan into the fire.
It's a difficult time with many looking back over the child rearing years and thinking "is this it, is this what I deserve, there has to be more from life"
How you resolve that depends on your boredom thresholds and how you problem solve, do you have the imagination to fill your time now the children are brought up with pursuits and learning, other than falling in love again.
Those in older age brackets see the devastation and pain the forty years can bring, I don't think it's a particularly kind age it's very competitive.
Next episode the 50's 😂