Help a girl out

So the boy I’ve been dating (for over a year) hasn’t OFFICIALLY asked me out yet. He introduced me to his family and referred to me as his girlfriend but he hasn’t actually asked me to be his. Btw I’m about to turn 18 and he just turned 19. He’s about to go into his sophomore year of college and I’m going into my freshman year. I really love him and he means a lot to me. But last night we were talking and he said that sometimes he gets the urge to distance himself, even if he’s really happy. He’s never really been close to anyone besides me, he doesn’t even open up to his friends. He’s very private and has a really hard opening up to people. He likes being alone, and he says the only reason he hasn’t ghosted me (randomly stopped talking to me) is because he knows I love him and I’ve been nothing but good to him. What could I do to make him feel better or idk??? I really want to make things official