No. Such a situation is highly unethical and goes against the principles of loyalty and respect in a relationship. It involves inappropriate and disrespectful behavior towards one's spouse and violates the boundaries of a committed relationship.
The relationship would be severely damaged. Trust would be completely broken. The husband would feel betrayed, and the wife would be in a very difficult position. The marriage would likely be on the verge of collapse.
It could lead to serious damage to reputations. The person who is the subject of such a false story, like the wife and her boss, may face social stigma and professional problems. Their personal and professional relationships could be severely strained.
There is no evidence to suggest that such activities occur in a gym environment. Gyms have rules and ethics in place to maintain a proper and respectful atmosphere for all members. This kind of description violates the basic norms of a public fitness place.