Yeah, my last exboyfriend had one of these too! He was obsessed with spending time with his mother. It was seriously codependent. He didn't do anything in the household -- cook, clean, nothing at all except sit around, eat massive amounts of takeout and restaurant food, and play video games all day.
I'll be honest, I was such a sucker that the very weird and overly close mother/son relationship wasn't even what finally put me off the relationship... it should've been a HUGE red flag, though. What adult child (ha -- I guess I could cut the world "adult" off the phrase) is willingly living with their parent at the age of 30? I don't care what the "circumstances" are that enabled the living situation, it's weird, codependent and not something a secure adult would ever choose to do!
I would say RUN! This isn't something you can change in someone else!