Well, this is an easy one, and the equivalent of the English: l'erba dalla parte del vicino e' sempre piu' verde. The grass is always greener on the other side (literally, the grass on one's neighbor's side is always greener).
This reflects the universal need to think that things are better elsewhere, somewhere. Being half Italian and half American, I am regularly exposed to Americans who think that Italy is a semi-paradise ("how could you leave?") and Italians who think that Italy is intolerable and are thinking of expatriating. Both are wrong.
In the words of one of my favorite poets, the Frenchman Charles Baudelaire (photo): "Cette vie est un hôpital où chaque malade est possédé du désir de changer de lit." Life is a hospital where each patient is obsessed by the desire to change his bed.
