cheating heart; temptation to cheat
Refers to a person's inclination or desire to be unfaithful in a romantic relationship. Often used in contexts of emotional or physical infidelity.
We broke up because of his cheating heart.
I couldn't suppress the temptation to cheat.
Compound of 浮気 (うわき, 'cheating, unfaithfulness') and 心 (こころ, 'heart, mind'). The exact historical derivation is uncertain, but the combination directly conveys 'a heart inclined to infidelity'.