Well, context is important. Remember; not caring is the default. He needs a reason TO care, not a reason not to. If he’s your bf or something & you know he DOES care, then: He probably doesn’t know what to say. The more you have to say about them, the more complicated he’s assuming the problem is. If he can’t say anything to make you feel better, ‘do no harm’ seems like a better second choice than ‘argue and throw some gasoline on that fire’ That way, best case, you have the space you need to
calm down on your own and y’all can address whatever it is more straightforwardly when the dust has settled a little and you have a chance to see the problem clearly. And worst case; at least if things deteriorate further it wasn’t his fault for saying/doing something stupid or walking into a trap. Note; he otherwise almost certainly would. He may even be right about there being no right thing for him to say. Is that the case?