Is wrestling adultery?

No. Adultery is defined as:

Adultery - extramarital sex: a married person having voluntary sexual relations with someone other than their spouse.

As a sport, wrestling has nothing to do with sexual intercourse. It is a game of physical contact, not unlike football, or many forms of Martial Art which are designed to promote health, and improve skills that can be used in self defense, or unarmed combat as in the case of soldiers defending their country.