|1.||a romantic or sexual relationship, esp a temporary one, between two people|
|2.||a great enthusiasm or liking for something: a love affair with ballet|
An intimate sexual relationship, as in They had a torrid love affair many years ago. This expression dates from about 1600, when it referred merely to the experiences connected with being in love. The current sense dates from the second half of the 1800s.
A strong enthusiasm, as in We can't ignore America's love affair with the automobile. [Mid-1900s]