Talking about breaking up

So my fiancé sometimes does this thing and he talks about what we would do if we break up, for example he will say something kinda joking like “petie is going with me if we ever break up!” (Our dog). Or he will make comments like “there’s only a couple things that would break us up I think”.

Like okay yes I understand it’s a possibility and everything but I just don’t like it when he talks about it like that. Kinda reminds me of how a family member will talk about when they die, like obviously everyone dies but I don’t wanna hear about it because it makes me sad. Am I being silly?

Like with my best friend, we are always going to be friends no matter what happens and that’s what we remind each-other when things are tough or we are sad, I guess I kinda just wanted it to be like that with my fiancé since we are getting married and everything but I guess that’s just a different relationship dynamic?