fair-weather friend

Cultural  

1. A friend who supports others only when it is easy and convenient to do so: “I thought Gene would always stick by me, but when I got into trouble, he turned out to be a fair-weather friend.”

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fair-weather friend Idioms  

1. A person who is dependable in good times but is not in times of trouble. For example, You can't rely on Sarah—she's strictly a fair-weather friend. This expression likens fair weather to good times. [Early 1700s]

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Example Sentences

If a fair-weather friend is someone who only comes around when things are good, a bad-weather friend is someone you can depend on when things take a turn for the worse.

From Los Angeles Times

The informality of their pact means that they’re only fair-weather friends: One won’t necessarily go to war just because the other does.

From Washington Post

The collection explores the dichotomy between deep and lengthy bonds, like Jane and Fiona’s, and fleeting encounters with lovers, fair-weather friends, colleagues, even parents.

From Washington Post

“We established All Seasons Press to be a publishing house that stands by our authors, rain or shine. We aren’t fair-weather friends.”

From Washington Times

In a pointed statement in the All Seasons news release, Ms. Burke said: “We established All Seasons Press to be a publishing house that stands by our authors, rain or shine. We aren’t fair-weather friends.”

From New York Times