I'm writing as the wife of one of these adult children. I'm merely reflecting, but...
DH and his sibling, both in their late 30s, have returned home to their parents several times after relationships have failed.
He has very doting parents, who don't discuss any of the issues around why they're home again each time but merely accept them back, with open arms. Meals cooked for them, clothes washed, ticketyboo. I would say that both DH and his sibling have struggled to ever really become independent from their parents, relying on them for regular practical help all their lives through to adulthood. Their parents will even remember when their cars MOTs are, collect them after boozy nights out, give them financial advice and often, financial support.
This is odd, isn't it, that one of them returns home again every couple of years?
When I left home, my parents divorced and bought separate one bedroom flats for themselves so I never had the luxury of going home. I have had to stand on my own two feet and perhaps this is why I've ploughed all my efforts into making my marriage work. DH just seemed to give up and moved back there without much resistance after I suggested separation when all my efforts were met with apathy and resistance.
Is it pure coincidence that my ILs grown-up children keep going home? Do you think their parenting is to blame?