My research suggets that in SC, clearly sexual intercourse is adultery but other acts may be considered to be a form of infidelity as well.Additionally, there need not be a showing of direct proof; the innocent spouse need only show circumstantial evidence that the spouse had an "inclination" to commit adultery and they had the opportunity to do so.  Note: Proving inclination can be done several ways: photos, love letters, texting, emails, or other written material. Also, joining online dating sites or dating applications on the accused spouse's cell phone may be used as evidence. At this point, you should consult directly with an attorney who is licensed in SC for further state specific information.