In some fictional settings, there might be a cultural or religious obligation within the context of the story. The hero might belong to a society where such an unusual marriage is seen as a solution to a problem. For instance, if the 'her novel' is personified as a deity or a very important figure in their fictional lore, marrying it could be a way to restore balance or gain favor.
One possible reason is a misunderstanding. The hero might think that they are in love with the person they marry, but later find out it was all a mistake. For instance, they might have misinterpreted their feelings of friendship or gratitude as love. Also, external threats could be a factor. If there is a threat to the hero's family or community, they might marry someone else as a way to protect them.
It could be that the 'novel' is personified in some way. In a fictional world where stories can come to life, the hero might be obligated to marry the story (novel) itself. This could be due to a prophecy that says marrying the novel will bring peace or some great benefit to the world he lives in.
One possible reason could be that the hero has a bad reputation in the society they live in. Maybe he is known for being a playboy or having a cruel streak, which makes the heroine despise him.
One challenge could be the acceptance of the relationship by others. People around the hero might not understand this strange union and could be hostile towards it.
It's also possible that she had some sort of accident or injury that affected her ability to control her bowels. For instance, if she had a fall or an impact on her lower abdomen area, it might have caused internal damage that led to the loss of bowel control. Or she might have been taking certain medications that had side effects on her digestive system, causing unexpected and uncontrollable bowel movements.
One reason could be to protect the person he marries. If she's a commoner, for example, the noble society in Camelot might not accept their relationship. So, they keep it a secret. Another reason could be that the person he marries has some sort of power or identity that could put them in danger if it was known. For instance, if she was a sorceress, in Camelot where magic is feared, they'd have to marry secretly.
Well, it could be that there was an emergency situation. For instance, if there was a fire or a water leak and she had to quickly remove her clothes to deal with it, like if she needed to use a wet cloth to stop a small fire and got caught in the process. Or perhaps she was sleepwalking and ended up in an unexpected situation where she was naked and got caught.
It might be a way to get her partner's attention in a very direct way. In a story, the wife may feel that her partner has been ignoring her or not taking her seriously enough, so she uses this rather extreme but effective method to make sure he focuses on her and her needs.
One reason could be her own curiosity. For example, if she ignores warnings about a dangerous area like an old, haunted forest or a restricted island. Another could be bad luck, like being in the wrong place at the wrong time, such as in a monster - infested area during an unexpected migration of man - eating beasts.
One reason could be physical injury. For example, if you break a bone or get a deep cut, the intense pain can make you cry. Another reason might be emotional distress that is so overwhelming it manifests physically as pain and crying, like when you lose a loved one or go through a major disappointment.