impulsivity

What is the best way to deal with impulsivity?  It is an impulse when a ADHD spouse keeps going to the same female in his adult life?  If i understand correctly, his first marriage ended because of this female and for all predicable purposes this marriage is over.  He will not talk about this person.  If i bring this person up he shuts down.  I feel nothing will improve unless both parties are open and honest.  After reading Mrs. Orlov book, he has decided to do little things around the house.  That is him trying to make an effort.