We are often not satisfied and want to be somewhere else; a place that is far away or different seems better than where we are. John is always changing his job because the grass always looks greener to him on the other side of the fence.
GRASS IS ALWAYS GREENER ON THE OTHER SIDE OF THE HILL
Meaning of GRASS IS ALWAYS GREENER ON THE OTHER SIDE OF THE HILL in English
American idioms English vocabulary. Английский словарь американских идиом. 2012