Something very much like this happened in the case of my stepson. He lived with my ex-wife, that is, his mom, until he was 40, all but about 5 years total that he was away at school. He had medical issues and was on disability.
Then my ex died last year - maybe I already told you about this? - and he was forced to figure out what to do. Fortunately his brother was able to help him get on his feet. He is working and now says, "lots of people worse off than me are working, so..." Yet when his mom was dying he was absolutely freaking out.
He is still living with his brother and sister-in-law. I visited this year. One thing I wondered was, "are they getting on each other’s nerves?" I had previously, last year, visited and advised him to get out on his own, get a girlfriend, you know, a "life." He said he was saving money to that end.
But when I was there this year they seemed like a family. I didn't pick up any vibe that they were secretly looking daggers at each other. I thought, "who am I to advise breaking up this family?" so I held my peace.