Two-time (verb)

To cheat on one's romantic partner by seeing someone else secretly.

Origin:

Late 19th century: from two + -time (as in one-time).

Examples:

1. He was two-timing his girlfriend with another woman.
2. She two-timed her husband with her co-worker.
3. He two-timed her and she broke up with him.
4. She felt betrayed when she found out he was two-timing her.
5. Two-timing is considered a form of infidelity.