something like Marquis de Sade but not as evil and monogamy?

Hii guys,

I feel like there must be many books but so far I couldn‘t find one that is not smut.

I am interested in the psychology behind it all and good conversations, interesting and complex storyline but involving 2 people who are in love, no orgies..

It should really go beyond sex.

DISCLAIMER: I am not interested in smut or something purely sexual.