lover-boy (n.)

"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.

mid-13c., boie "servant, commoner, knave" (generally young and male); c. 1300, "rascal, ruffian, knave; urchin," mid-14c. as "male child before puberty" (possibly extended from the "urchin" sense). A word of unknown origin.

Possibly from Old French embuie "one fettered," from Vulgar Latin *imboiare, from Latin boia "leg iron, yoke, leather collar," from Greek boeiai dorai "ox hides." (Words for "boy" double as "servant, attendant" across the Indo-European map — compare Italian ragazzo, French garçon, Greek pais, Middle English knave, Old Church Slavonic otroku — and often it is difficult to say which meaning came first.)

But it also appears to be identical with East Frisian boi "young gentleman," and perhaps with Dutch boef "knave," from Middle Dutch boeve, perhaps from Middle Low German buobe. This suggests a gradational relationship to babe. Another conjecture:

In Old English, only the proper name Boia has been recorded. ME boi meant 'churl, servant' and (rarely) 'devil.' In texts, the meaning 'male child' does not antedate 1400. ModE boy looks like a semantic blend of an onomatopoeic word for an evil spirit (*boi) and a baby word for 'brother' (*bo). [Liberman] 

Used slightingly of young men in Middle English, also in familiar or contemptuous use of criminal toughs or men in the armed services. In some local uses "a man," without reference to age (OED lists "in Cornwall, in Ireland, in the far West of the U.S."). The meaning "male negro slave or Asian personal servant of any age" attested from c. 1600.

Extended form boyo is attested from 1870. Emphatic exclamation oh, boy is attested by 1917. Boy-meets-girl "typical of a conventional romance" is from 1945; the phrase itself is from 1934 as a dramatic formula. Boy-crazy "eager to associate with males" is from 1923.

A noticable number of the modern words for 'boy', 'girl', and 'child' were originally colloquial nicknames, derogatory or whimsical, in part endearing, and finally commonplace. These, as is natural, are of the most diverse, and in part obscure, origin. [Buck]