c.1300, "love," from Old French amour, from Latin amorem (nominative amor) "love, affection, strong friendly feeling" (it could be used of sons or brothers, but especially of sexual love), from amare "to love" (see Amy). The accent shifted 15c.-17c. to the first syllable as the word became nativized, then shifted back as the naughty or intriguing sense became primary and the word was felt to be a euphemism.
A common ME word for love, later accented ámour (cf. enamour). Now with suggestion of intrigue and treated as a F[rench] word. [Weekley]