I think I disagree with the sentiment if your post. Mainly because this isnt about affairs. This happens in any split.
Yes, men often dont do enough when they leave. Though as I have got older i know quite alot of people whose mothers swanned off without a backwards glance in the 70s/80s/90s. Far more common than I had thought. It seems that a lot of people dont speak about that.
However, often the women want to keep the kids. Especially if they have made career sacrifices and are the main carer of the children.
So it makes sense, the children would stay with the mother. Hopefully, as times change more men will care for their children 50:50 within the relationship, and then continue that if the relationship ends.
Though, I have seen a change in tone on mn when it comes to this issue, in the 10 years I have been here.
When women are sahp, or work less than full time or are the main careers, it's always been that in the event of the divorce it's only right for the woman to pursue the man for everything they can get.
Yet more and more women are coming to complain that they are the main wage earners, their husband is a cocklodger (when actually it appears they work part time and are main carers of the kids) and arent happy their soon to be ex is saying half the house and pension that they have paid for. These men are demonized for wanting their fair share, or what was seen as a fair share when women are the low earner/main carer. And/Or for wanting to take the kids.
I think the next 10 years will see a huge shake up of how all these things work.
When me an exh split we did 50:50 as we did when married. But as time has gone on, the kids choose to be with me more. My Home is more stable.
Of course some men are shit and do just fuck off to their new life. But I do think alot of women would prefer to be the RP.
I think both men and women need to have a huge mental shift when it comes to kids and childcare, before equality has any chance of happening.