fair-weather
(of people 人) behaving in a particular way or doing a particular activity only when it is pleasant for them 同甘不共苦的;顺境中的 adjective only before noun disapproving

a fair-weather friend(= somebody who stops being a friend when you are in trouble) 不能共患难的朋友

have(got) friends in high places:有身居高位的朋友 to know important people with power and influence who can help you

Ask Bob to help with the campaign. he's got friends in high places.
让鲍勃在帮助进行这次运动吧,他在上层有些朋友.

He never did anything special in his life, but he had friends in high places.
他一辈子从未做过什么特别的事,但他有一些位高权重的朋友.

what's sth between friends?
used for refusing an offer by a friend to pay you ffor sth because the amount is small (区区小钱)朋友之间计较什么

'I owe you 50p for that coffee.'
'don't be silly, Steve, what's 50p between friends.'

"我欠你50便士的咖啡钱."
"说到哪里去了,史蒂夫,咱俩是朋友,50便士算什么?"