two-timing
noun1
The practice of being sexually or romantically unfaithful.
- His two-timing wrecked his marriage.
two-timing
adj1
Sexually or romantically unfaithful.
- That two-timing SOB really hurt my feelings.
- The troubles can be endless: a mix-up on meals, a shortage of liquor, engine difficulties, other mechanical quirks, male pinchers, female whiners, vomiting children, two-timing stewardesses who steal your man, and, once in awhile,^([sic]) a plane that takes a good friend to a fiery death.1967, Trudy Baker, Rachel Jones, Donald Bain (uncredited), Coffee, Tea, or Me?: The Uninhibited Memoirs of Two Airline Stewardesses, New York: Bantam Books, page 3: