Absence makes the heart grow fonder
The lack of something increases the desire for it.
The Roman poet Sextus Propertius gave us the earliest form of this saying in Elegies:
"Always toward absent lovers love's tide stronger flows."
The contemporary version appears in The Pocket Magazine of Classic and Polite Literature, 1832, in a piece by a Miss Stickland:
'Tis absense, however, that makes the heart grow fonder.
The phrase was also source material for the lewd wordplay:
"Absinthe makes the fart grow stronger".