He is loyal, honest, and faithful.
A great husband does not lie to his wife and is faithful to her. Infidelity is the last thing he would be caught doing.
This is not to say that he would never get tempted. Of course, he would get tempted because he is a human being. But what sets him apart from the cheating husband who is a jerk is that he can control himself and stay faithful to his wife because of the love he has for her and his commitment to their marriage.