Couples often avoid conflict because they believe it will cause divorce. We figured out that's when we have all of our fights. Conflict is inevitable. If there is more then one person, there is bound to be more than one opinion. Talk to each other.
Irritations can pile up and prompt criticism or a sarcastic comment.
It's best not to harp on a sore subject, but equally as important not to let things simmer until they reach a boiling point. Be an active listener. Try not to interrupt. Be willing to trade places. Try to be fair and objective.