Refers to a romantic or sexual relationship, often with a nuance of secrecy or impropriety. Commonly used in news and literary contexts.
He resigned from the company after his affair with a married person was exposed.
The novel depicts a forbidden love affair.
事情 means circumstances or reasons behind a situation, while 情事, the same two kanji reversed, means a love affair.
情事 means a love affair or romantic liaison, not the general emotional fervor meant by 情熱, despite sharing the kanji 情.
Compound of 情 (emotion, feelings) and 事 (matter, affair). The exact historical derivation is uncertain, but the combination naturally yields the meaning 'matter of the heart' or 'love affair'.