Maybe he likes having his mom do his laundry or cooking and pamper him, and maybe he saves heaps of money by living at home and ask some deal with his parents where he does inside outside work to live still at home, does he pay rent living at home ? Is he going to school and doesn't have a full time job? I had an ex live at home until around 25 yrs old, when he finished his uni degree, once he finished it and got a full time job he moved out. it never bothered me, he saved a lot of money for his future with the help of us parents.
“The one you love and the one who loves you are never, ever the same person.”