First, figure out the main problem. Maybe it's a plot hole or inconsistent characters. Then, think of logical solutions to fill those gaps or make the characters more coherent.
Anal sex can go wrong if there is no proper preparation. Preparation includes things like using enough high - quality lubricant. Without it, the friction can be extremely uncomfortable. Also, not warming up the area gently can lead to issues. And if either partner has underlying health conditions in the anal area like hemorrhoids, it can make the situation much worse and lead to a very unpleasant experience.
There might be a situation where the third person involved in the 'wife sharing' became too possessive. Say, a couple agreed to have a more open relationship and share the wife's company in certain social settings. But the new person started to demand more of her time and attention, causing jealousy and strife within the original couple.
Oh, there are many! Like when I planned a perfect picnic but it rained cats and dogs, and all the food got spoiled. That was a disaster but funny in retrospect.
Oh, it could be something like someone wearing traditional clothing from another culture for a costume party and getting completely bashed for it. Not a good look!
There might be disappointment. Say the wife dreams of a small, cozy home but the husband buys a large, modern apartment believing it's her fantasy. The wife will be disappointed as her real desire isn't met. Also, it can lead to a feeling of being misunderstood in the relationship. If this keeps happening, it can gradually damage the relationship and make the couple grow apart over time. It's important to communicate clearly about each other's fantasies to avoid such situations.
Insufficient local knowledge could also be the reason. Not understanding the local context, social structures, and existing resources might result in ineffective or inappropriate assistance.
Another consequence could be damage to the family unit. In a story where wife - swap goes wrong, there may be negative impacts on children if they are aware of the situation. It can cause confusion and emotional distress for them, as the family dynamic they are used to is disrupted.