雙宿雙飛

lit. to rest and fly together (idiom) / fig. to live in each other's pockets / to be inseparable

surname Shuang

two / double / pair / both / even (number)

old variant of 宿[su4]

surname Su

lodge for the night / old / former

night / classifier for nights

constellation

flying in pairs / close union as husband and wife / round-trip flight / (slang) threesome

to fly