fair-weather
adjectiveUK /ˌfeəˈweð.ər/
US /ˌferˈweð.ɚ/
Only staying a friend when things are easy and fun.
He was just a fair-weather friend who left when I needed help.
RELATED WORDS
OTHER MEANINGS
2. Relating to good, calm weather with clear skies.
The sailors set out in fair-weather conditions.
3. Suitable only for mild, pleasant conditions.
They wore fair-weather jackets for the spring hike.
4. Showing support only when things are going well.
The team had many fair-weather fans who vanished after a loss.