性病...................."

You will only get 性病 if u have contact with someone who carries the disease.
If both the husband n wife do not have 性病, and both of them did not have sexual intercourse with other infected people,
no matter how many times u have sex, u wont get 性病.

But better be careful of UTI (Urinary Track Infection), bcos' UTI could be cause by frequent sex