Boyfriend doesn't open up, what to do

So my boyfriend and I have been dating for 3 years now. I've learned that he's not an open book and he keeps his feelings deep deep down inside bottled in, which is fine with me because he opens up when necessary, like if he's upset with me or is feeling some type of way about something within the relationship. Anything that has to deal with us, he's open to discuss, but I'd never know what's going on in his personal life because he doesn't open up about that. And when he does, it's when he's had enough and he breaks down, it's really bad. But because he doesn't like to discuss personal issues, I don't press him about it and I'm just really patient with him. BUT I also don't ever ask about whatever is going on in his life. Like his grandpa is dying and they were very close and it's very stressful on him but he acts like he has no bother in the world. He's so strong but I know he's hurting. But I don't even ask questions like how is his grandpa doing because Idk if that's gonna trigger a breakdown and Idk if he's even gonna be willing to tell me, but sometimes I feel bad for not asking because I don't want it to seem like I don't care. I just don't wanna trigger him. So how can I show kind guestures to show my boyfriend that I do care and to share empathy with him without putting him in an uncomfortable situation like discussing his dying grandfather.