extramarital sex; affair; fooling around; infidelity; wantonness; unfaithfulness
to be fickle; to be frivolous; to be flippant; to be flighty; to be giddy; to be restless
adulterous partner (in a relationship); adulterous lover
cheater; unfaithful person; adulterer
prone to adultery; flirtatious
cheating heart; temptation to cheat on one's partner
female adulterer; adulteress