There is also a chance that she has some sort of business or work - related matter with the man. Perhaps they are colleagues and they left the party together to discuss an urgent project. It doesn't always mean there is something improper going on between them. Sometimes, social and professional boundaries can seem a bit blurry in such situations.
One possible reason could be that she suspects her husband of having an inappropriate relationship. Maybe she has noticed some strange behavior or changes in her husband's attitude towards this man, like being overly secretive or showing excessive interest. Another reason might be that she is just curious about their friendship and wants to understand it better.
The husband should first try to stay calm. Reacting impulsively can make the situation worse. He could start by having an open and honest conversation with his wife when she returns. Just ask her directly about why she left with the other man.
One reason could be dissatisfaction in her current marriage. Maybe she feels unloved or ignored by her husband. For instance, if her husband is always busy at work and doesn't have time for her, she might be tempted to seek attention elsewhere.
One possible reason could be a breakdown in the relationship where she might have felt neglected and sought emotional or physical connection elsewhere. Another reason could be a momentary lapse in judgment, perhaps due to alcohol or drugs. It could also be the result of an ongoing affair if she has fallen in love with someone else.
One reason is to connect with others. By sharing her stories, she can find common interests or experiences with the party guests. For example, if she shares a story about her experience with a particular book, and someone else at the party has read it too, it can start a great conversation.
It could be a completely innocent reason. For instance, she might be helping out a friend. Maybe the man is in a difficult situation and she's just being kind.
Well, perhaps in the fanfiction they leave because of a prophecy. A prophecy might state that their presence near Hermione would bring great danger to her or to the wizarding world as a whole. So, they sacrifice their friendship and leave. Also, it could be due to some dark magic influence. They are forced by a powerful dark magic spell to stay away from Hermione, not having control over their actions.
In some fanfictions, Naruto might leave because of a rift within the village. If there are political factions that oppose him or his methods, and he feels that he can no longer operate effectively within the village, he may choose to leave. This could also be due to a misunderstanding or false accusations against him that he can't seem to clear up while remaining in the village.
One possible reason could be that Sakura realizes Sasuke is on a path she can't follow. Maybe he's too consumed by his revenge and she decides it's better for her own well - being to leave him be. In some fanfictions, she might also find someone else who values her more and she chooses to focus on that new relationship instead of chasing after Sasuke.
She might be an introvert. Introverts often feel drained in social situations like parties. They prefer quieter, more intimate settings and large parties with lots of strangers can be overwhelming for them.