unfaithful
He was utterly ignorant of his wife's unfaithfulness.
"I will not accept unfaithfulness in marriage," she says firmly.
She found it difficult to forgive his unfaithfulness.
SMART Vocabulary: related words and phrases Disloyalty, betrayal & treason
adulterous
backstabber
betrayal
betrayer
break ranksidiom
chicane
deserter
desertion
faithless
faithlessly
faithlessness
false
fifth column
sellout
stab someone in the backidiom
tergiversation
throw someone to the lionsidiom
throw someone under the busidiom
treasonable
unfaithful
You can also find related words, phrases, and synonyms in the topics:
Relationships: infidelity