"one who is enamored, person in love," early 13c., agent noun from love (v.). Old English had lufend for male lovers, lufestre for women. Meaning "one who has a predilection for" (a thing, concept, pursuit, etc.) is mid-14c. As a form of address to a lover, from 1911. Related: Loverly (adj.) "like a lover, suitable for a lover" (1853); loverless (1819).
Lover's quarrel is from 1660s; lover's leap, usually involving a local crag and a fanciful story, is by 1712; Lover's Lane for a remote and shady road, little-traveled and thus popular with lovers, is by 1853. It seems also to have been an actual road-name in some places.