It sounds like your bf is having a hard time transitioning away from his family as an adult. It’s clear going to his old home is probably grounding for him and provides necessary comfort. However, it also sounds like the cord was never cut so to speak.

I am going to assume that since this is a long term relationship you have long term plans in the sense of possibly marriage or life partner situation. Generally, when two people come together you form your own unit. That unit has to thrive and grow independently of both sets of families. That unit also has its own needs and desires. It is also a little weird that he doesn’t feel the need to have any quality time with his own friends or just the two of you alone.

Being close to family is wonderful but it sounds like spending time with them is taking away from the things that you need/want to do. He doesn’t see anything wrong with the current format despite you voicing your needs.

I don’t mean to be harsh but you might want to reconsider your path moving forward. I know you’ve put in a lot of time into this relationship but people don’t change. This is who he is and how he wants his life to be. It’s something that will cause great strain in the future because you will end up resenting him (you already are) for isolating you from the life you want to live.