American English, early 20th century—primarily used of a present that delivers repeated enjoyment in the course of time—also sarcastically used of a person or situation constituting a recurring problem
‘air guitar’: an imaginary guitar played by miming, especially to rock music—‘air band’: a pretend rock band whose members mime the action of playing imaginary instruments—USA, 1978
a fantastical or idealised story, situation, etc., involving romance—USA, 1928—a blend of either the noun ‘romance’ or the adjective ‘romantic’, and of the noun ‘fantasy’