dirty love; sordid love
Refers to love or affection that is morally impure, lustful, or indecent. Often used in literary or critical contexts to describe a relationship driven by base desires.
That novel depicts a forbidden, sordid love.
Compound of 淫 (indecent, lewd) and 愛 (love). The exact historical derivation is uncertain, but the combination is transparently associated with impure or lustful affection.