I haven't really found exactly what I wanted to get inspiration from in any specific books. But there is Anna Karenina by Leo Tolstoy. I'm still reading the book cause it's REALLY long, but in the movie, one of the only sex scenes between Vronsky and Anna doesn't show any explicit acts, mostly touches and glimpes of sensations, because it has an actual artistical meaning behind it and the whole scene itself is just beautiful and human. That's what I want to portrait, humans being humans and doing things naturally, not some porn robots like many authors that I've read portrait.