Cheating on someone, or being cheated on (read more about infidelity here), represents one of the more traumatic events that can occur in any romantic relationship. Although the reported incidence rate of infidelity varies considerably by sample and relationship type, suffice it to say that affairs are not uncommon in marital and non-marital relationships. And people (in those relationships) suspect it’s common – when asked, people generally presume that people cheat frequently (hence the prevalence of tabloid magazine lists on ‘how to spot a cheater’).
Yet, despite the apparent widespread presumption that staying true to another is no easy task, people likewise presume their own partners are highly unlikely to stray. A number of studies, mostly focused on married individuals, have documented a clear gap between the frequency of infidelity (i.e., people admitting they have cheated on their spouses) and individuals’ expectations that their partner has cheated. Basically, people believe others cheat, and even report doing it, but still don’t tend to think it has happened, or will happen, in their relationships.