I feel that broad overgeneralizations like this are often just self-revelation.
This reads like you find people besides your wife attractive, but rather than recognizing this as normal and healthy, you vilify and repress it. But you see (part of) the responsibility for avoiding your thoughts with others, and expect of them to act according to your needs and wants.
The thought of people of the other gender using a toilet near you is sexual to you and you don't like that, but this is a you problem.
Also, I don't know whether your "stably married mother/father" is just heteronormative or deliberately excluding same-sex couples, but if it's the latter, your "belief" is demonstrably wrong. [1]
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6309949/
