Lechery

[Kai]

Excessive or offensive sexual desire; lustfulness.

[Monty]

[lech]·er·y
n. pl. lech·er·[ies]
Excessive indulgence in sexual activity; lewdness.
A [lecherous] act.

[Dave Paprocki]

Illicit or extra-marital sexual activity. See also: [adultery], fornication.
It is a [high-brow] word to help you sound more sophisticated as you explain why you are no longer married.
A related term is mental [lechery]...its pretty self-explanatory.

[Luis Fok]

behaviour, especially by men, that shows a strong sexual interest in someone: