The document discusses relationship infidelity and provides signs that a partner may be cheating. It defines infidelity as unfaithfulness to a sexual partner. Relationship infidelity can be emotionally destructive and is a common occurrence, with statistics showing that some percentage of people in relationships or marriages engage in infidelity. The document then lists various signs that a partner may be cheating, such as changes in appearance, mood, behavior toward their partner, increased time spent away from home, changes to communication habits, and other telltale signs that could indicate an outside relationship.