In another scene, Oppenheimer and Jean Tatlock sit facing each other while naked. Plus, there's a more psychological sex scene where Oppenheimer is at a hearing where his affair with Tatlock comes up, and his wife, Kitty (Emily Blunt), envisions her naked husband sitting there while a naked Tatlock rides up against him. It's more sex than people may be accustomed to with a Christopher Nolan movie, but honestly, it's fairly tame.
The online hype appears to come from people misunderstanding the situation and being excited about Nolan going whole-hog to film some sex scenes. Additionally, nothing ever comes across as gratuitously raunchy. It may be uncomfortable if you're watching the scenes with your parents, but "Belle de Jour" this is not. This may cause one to wonder why the sex scenes are there in the first place. While "Oppenheimer" mostly focuses on the titular character's involvement in the development of the atomic bomb, it also presents him as a multifaceted person with an interest in socialist ideas and a bit of a womanizer.
Oppenheimer cheated on Tatlock with Kitty, and after he and Kitty got together, he had an affair on her with Tatlock. Both women played important roles in his life, and he was clearly a sexual being. The hype surrounding the scenes prior to the film's release likely had more to do with Nolan avoiding such moments previously in his filmography. It probably wasn't worth an entire media cycle in the end, but if it gets people in the seats, that may be all that matters.
"Oppenheimer" is playing in theaters now.