For the health of both sides.

As long as both parties are healthy and can ensure that the other party is their only sexual partner, they will not get sexually transmitted diseases. Sexually transmitted diseases are caused by bacteria or viruses. As long as there is no pathogen, of course, you won't get sick.

But sometimes even if both parties have no history of deviance and have bad living habits, such as not washing their hands effectively before and after going to the toilet, going to public bathhouses, swimming pools and other places where pathogens can spread, they may be infected.

At the same time, women are more likely to get sexually transmitted diseases than men. Because the female genitalia is dark and humid, it is very suitable for the growth and reproduction of pathogens.