I think it’s the person who doesn’t initiate the break up that gets the raw deal.
if you’re the one planning your exit, you usually have your ducks in a row. Whether that’s a new partner, squirrelled away some cash, or other plans. You have the power and control. While the other partner doesn’t want to break up so remains trusting and doesn’t see what’s happening.
so yes, if a bloke walks out the woman is often left with the kids struggling. Often as a sahm or a pt mum.
however if it’s the wife that initiates the break up- I won’t say walks out as she normally stays in the family home- then it’s him who’s left back at his mums not seeing his kids full time, with no way of getting back on his feet financially and buying/renting somewhere.
it also depends on the finances. If you’re down south on an average salary, there’s no way that house can be sold to buy two properties. So one ends up staying and the other leaves with little. If you both have decent jobs you can support yourselves and things are much easier.
which is why I would never give up work or my financial independence. Dh walks out, or dies, I am fine financially. Same for dh, he supports me working and does his share of house and kids- now you might say that’s a second wife thing, but he learned form his ex when she wanted to be a sahm. He supported that as well, but found himself working shit loads of overtime to support them, plus she was (understandably) drowning in full time childcare and house around that, so he was working 7-3, picking the kids up to give her a break til they went to bed, then logging back on until midnight.
i wonder if first marriages tend to jump into the traditional, whereas second marriages less so as both parties are more independent/financially secure.