love-seat n.

Old English lufu "feeling of love; romantic sexual attraction; affection; friendliness; the love of God; Love as an abstraction or personification," from Proto-Germanic *lubo (source also of Old High German liubi "joy," German Liebe "love;" Old Norse, Old Frisian, Dutch lof; German Lob "praise;" Old Saxon liof, Old Frisian liaf, Dutch lief, Old High German liob, German lieb, Gothic liufs "dear, beloved"). The Germanic words are from PIE root *leubh- "to care, desire, love."

The weakened sense "liking, fondness" was in Old English. Meaning "a beloved person" is from early 13c. The sense "no score" (in tennis, etc.) is 1742, from the notion of playing for love (1670s), that is, for no stakes. Phrase for love or money "for anything" is attested from 1580s. The phrase no love lost (between two people) is ambiguous and was used 17c. in reference to two who love each other well (c. 1640) as well as two who have no liking for each other (1620s, the usual modern sense).

To fall in love is attested from early 15c.; to be in love with (someone) is from c. 1500. To make love is from 1570s in the sense "pay amorous attention to;" as a euphemism for "have sex," it is attested from c. 1950. Love affair "a particular experience of love" is from 1590s. Love life "one's collective amorous activities" is from 1919, originally a term in psychological jargon. Love beads is from 1968. Love bug, imaginary insect, is from 1883. Love-handles "the fat on one's sides" is by 1967.

"Even now," she thought, "almost no one remembers Esteban and Pepita but myself. Camilla alone remembers her Uncle Pio and her son; this woman, her mother. But soon we shall die and all memory of those five will have left the earth, and we ourselves shall be loved for a while and forgotten. But the love will have been enough; all those impulses of love return the love that made them. Even memory is not necessary for love. There is a land of the living and a land of the dead and the bridge is love, the only survival, the only meaning." [Thornton Wilder, "Bridge of San Luis Rey," 1927]

c. 1200, sete, "thing to sit on; place one sits," from Old Norse sæti "seat, position," both from Proto-Germanic *sæt- (source also of Old High German saze, Middle Dutch gesaete "seat," Old High German gisazi, German Gesäß "buttocks"), from PIE root *sed- (1) "to sit." Old English had sæt "place where one sits in ambush," which also meant "residents, inhabitants," and is the source of the -set in Dorset and Somerset.  

The sense of "part of a thing (a saddle, etc.) on which one sits" is from c. 1400. The meaning "posterior of the body" (the sitting part) is from c. 1600; the sense of "part of a garment which covers the buttocks" is from 1835. Seat belt "safety restraint when sitting" is from 1915, originally in airplanes.

By late 14c. as "part of the body in which a humor arises;" from 1550s as "site, situation, location" generally.

The word in the sense of "residence, abode, established place" (late 13c.) is an extended use of this, influenced by Old French siege "seat, established place," and Latin sedes "seat." It is perhaps from the notion of a chair set apart for the holder of some position of dignity or authority (a sense attested in English seat from c. 1200). The meaning "city in which a government sits" is attested from c. 1400. The sense of "right of taking a place in a parliament or other legislative body" is attested from 1774.