Archaic noun for mutual love or being in love with each other. Not used in modern everyday Japanese; encountered only in classical literature or historical contexts.
In classical literature, the word 相惚れ was used to express mutual love.
Compound of 相 (mutual) and 惚れ (falling in love, from verb 惚れる). The exact historical derivation is uncertain, but it follows a pattern of classical compounds expressing reciprocal states.