Why does he act like that when I confront him?

Whenever I confront my boyfriend about something he did/said that upsets me, he gets all quiet and avoids the conversation. He’s always been like this. When I try to talk to him he doesn’t say anything, doesn’t look me in the eyes, doesn’t care to ask why I feel that way or even apologise. He just nods, grunts, or says “uh huh”. He never takes accountability or responsibility for anything and nothing gets resolved because he doesn’t acknowledge how I feel or even try to understand. It’s like he doesn’t care about my feelings and like he doesn’t want to talk about our problems. Every time I want to talk about something it just feels useless because it’s never gonna get solved, he’s not gonna want to talk about it or take some responsibility. I don’t know what to do