It's clear in Jack's case that he's the one who's suffering. It seems as if he hasn't fully comprehended how much his wife loves him; it's as if he's a little overwhelmed by it all.
It's likely that she projects her desire for a father figure onto her husband. It's practical for her since she becomes the perfect mother of an ideal father without the risk of conflict with her own mother. Love is often a game of narcissistic mirroring*. Love reaches maturity when you manage to rid yourself of this game.
This story illustrates the difficulties that may be encountered when the age gap is quite large. He's ill, he can no longer satisfy her. He longer feels like a man around her.
Couples or relationship counseling could be beneficial for this relationship. Developing an understanding of each other's points of views in times of trouble can help you to relate to each other as a couple and rediscover why you fell in love in the first place.
*narcissistic mirroring is when the narcissist's partner changes in order to conform to the narcissist's values and requirements.
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