Why doesn't he care about what I'm up to?

Sounds like a self absorbed idiot to me, you shouldnt be made to feel that way especially in a relationship. God i find my bfs airsoft hobby boring but i still listen and listen to his skirmish adventures and ask about stuff being interested tbh its a load of men running around playing soldiers but jesus in a relationship u gotta show some interest, tell him how u feel and if hes the same find somebody who is intrested in you.