I’d be sorry for all their kids if they split up, because even with his obvious failings, Josh is still generally a more positive influence in their life than their mother.
If he did leave her, I wonder whether Rachel would finally accept that
she is the main problem? If you had failed relationships with all three of your kids’ fathers (and estrangements from several family members), surely it would encourage a modicum of self reflection?
Despite his inadequacies, I do genuinely think Josh wants to be a good father, and that given the right support he would be fine. But unfortunately for him he’s stuck with an abusive partner who is emotionally stuck at the age of around 13, unable or unwilling to parent effectively, and who knows he’s neurodivergent and uses it to her advantage. It’s sad, for everyone impacted by her toxic nature.
Also, whilst Josh might struggle with some of the symptoms of his autism (my view only, I know he hasn’t sought diagnosis) he also isn’t stupid and can see very clearly how awful Rach would be to him if they split. He’s observed close hand that she can and will manipulate situations to her advantage (and his, when it came to his sons). I think he’d rather live with her on his side, than pit himself against her. He’d lose, and he knows it.