to be honest i don't think he's a yandere- (although it's possible that he is), one of my theories is one of the reason why he acts like that is because his wife ill seriously affects him and he fell guilty, and probably she has already been in a state close to dead and that has he's traumatized, that's why he's so embarrassed and protective about it, aslo that's why he freaks out when we ask him if his wife is dead.
aslo one of my theories(it's more a headcanon) is that he has a mental disorders or he has autistic disroder, that's why sometimes he responds in a weird way or he can go very far away when he talks
(btw sorry if my english is very bad and some things are poorly expressed :'()