If a problem solving discussion gets heated and anger is mounting, establish a time-out procedure. Remember to set a time and date for resuming discussion if a time out is instituted. To diffuse conflict, use soft emotions. Normalize some disagreement. The old adage that you can agree to differ is always useful to remember.
Nobody has to win in a disagreement.
Rather, the focus can be on each partner listening to and understanding the other's point of view. Develop your own autonomy. In order to prevent resentments you might take your partner's dissertation writing time to increase your own autonomy. Autonomy can be a self- esteem builder. Balance autonomy with connection.