The term 'was unfaithful to' can be summarized by two crossword solutions: STRAYED (7 letters) and cheatedon (9 letters). This phrase is used to describe a situation in which someone has been unfaithful to their partner or spouse, either through physical or emotional infidelity. STRAYED implies that the person has gone astray from their relationship, while cheatedon implies that they have been unfaithful by engaging in an affair with another person.