attack the action, not the person
If you are having a fight with someone in a relationship, you should treat it as the two of you versus the problem, instead of you versus them. Does your partner want to eat spicy food and only cooks that? Find a solution that makes the both of you happy instead of trying to “win” over them.
If your friend accidentally microwaves a metal spoon, saying “well that was a dumb move” is a funny way of making light of the situation. Saying “wow you are dumb” is an attack against their character.