unfaithful
adjective
-
not trustworthy“an unfaithful reproduction”
-
not true to duty or obligation or promises“an unfaithful lover”
-
having sexual relations with someone other than your husband or wife, or your boyfriend or girlfriend“Their spouse was unfaithful.”
-
having the character of, or characteristic of, a traitorfaithlesstraitoroustreasonabletreasonous