I am perfect!!! 😠

No i know am not perfect but my husband always complain that i should gain some weight get bigger as .. i am
underweight i eat but i cant gain weight i had this problem since i was little , when he said that to me i said no i dont need to change i am perfect the way i am.. and he just smiled ... how would you react if your husband/boyfriend said that to you? i feel insecure and i dont know what to do!!! because i know i cant gain weight 😞