It is not appropriate at all. Watching sexual content together, especially with an ex - girlfriend, violates normal moral and ethical boundaries. Such behavior can be considered inappropriate and disrespectful to the concept of healthy relationships.
One consequence would be the destruction of the marriage. The husband would likely feel violated and may not be able to forgive such a transgression. Additionally, it could cause emotional trauma for the wife herself in the long run as she may come to regret her actions. It can also make her a target of unwanted attention from the stranger or others who hear about it, which could put her safety at risk.
One consequence could be the end of the friendship. The friend may feel extremely uncomfortable and violated, and may not want to have any further contact with the couple. Another consequence is that it can damage the couple's own relationship. They may later regret their actions and feel that they have crossed a line that they shouldn't have.
One benefit is that it can expand his vocabulary. As he watches the story, he'll hear new words and phrases, which is great for his language development. Also, it can stimulate his imagination. The story's plot and characters can inspire him to create his own little worlds in his mind. Moreover, it might help him learn about different values and morals through the story's message.
It's not a good idea. Sexual stories usually involve adult - oriented and often inappropriate content. There are much better and more positive forms of entertainment like reading classic literature, watching educational documentaries or engaging in hobbies.
This is clearly inappropriate. In a healthy relationship or any situation, one should not force another to engage with sexual content. It goes against respect for personal autonomy and can have a negative impact on the person's mental state. If it's a relationship, it may even lead to the breakdown of trust and a healthy dynamic between them.
One way is to introduce her to various genres of positive literature, like science - fiction or historical novels. For example, '1984' by George Orwell is a great read that can engage her mind in a different way.
As the title is not clear in a proper context, it could potentially be about the themes of loyalty in friendship if we assume 'big friend' means a very important friend.