This is a tricky question for me only because we do not know what Ennis' marriage was like prior to his wife's diagnosis. It is quite possible that Ennis' wife created a routine in the home that worked best for her and the children given the amount of time Ennis was absent. Could his presence have created more stress in an already stressful situation if all of the sudden he was home? I wonder if Ennis had a habit of being emotionally uninvolved while home, only counting down the days until his return to sea. His wife knew she would already be dealing with a lot during her sickness, maybe she had no desire to deal with his moodiness on land. Maybe she wanted to keep some type of regular schedule going- -mom stays home, dad goes to work- -so things looked more normal for the children. His constant presence may have scared them; communicating to them that something was terribly, terribly wrong. She may not have been ready to deal with that.
Ennis obviously felt guilty. But I feel like he was damned if he did, damned if he didn't. He did what his wife asked him to do. Soooo, he is selfish, uncaring, uninvolved, a jerk. If he had ignored her request and stayed, one could still say he is being selfish- -thinking about what he wants, not his wife. Was his wife trying to be manipulative? If so, why?
I don't think Ennis' wandering was the same as Franny's UNTIL this trip. His was related to his job. However, fear of his wife's deterioration and sole responsibility for his children drove him to run away rather than confront it. Having run away from so many people close to her while they were living, Franny had a different perspective now that they were all lost to her. She communicates the importance of physically being there to Ennis in her attempt to convince him to return. On the other side of not being present for her husband, her mother, and her grandmother, Franny sees the harm that did and can do. (She even took her own advice, ultimately, at the very end of the book when she fought to STAY.)