Ivan took his position as Atlanta's mayor very seriously. He put on a brave face and did what a leader is expected to do during a time of tragedy-hold it together for the people he served. When he came home, he tried to manage his wife's behavior, treating her more as a constituent than a spouse. By doing so, he was unable to let down his guard and show his true feelings.
I think Ivan hoped his wife would assume the role of "leader's wife" and behave similarly. He was not prepared for her to be so incapacitated by her grief. I think if Lulu had not been so overwhelmed or dramatic, Ivan may have had the opportunity to ask her for comfort long before his emotional breakdown