Several hours later, when Julien left Madame de Rênal's room, one might have said, as they say these things in romantic novels, that he had nothing else to desire. (1.15.18)
Stendhal has a not-so-subtle way of telling us that Julien has had sex with Madame de Rênal, probably more than once. He decides to couch this claim in the language of romance novel. When he says that Julien "had nothing else to desire," he's saying that all of Julien's sexual urges have been satisfied. Bow chicka bow bow.
Even when there was nothing left to refuse him, she pushed Julien away, her indignation very real, and then threw herself into his arms. (1.15.20)
Madame de Rênal doesn't know how to act after she's committed adultery with Julien. First she pushed him away, then she throws herself into his arms. It's a concrete, physical way of showing that she doesn't really know what to do.
"If I ever get to leave the seminary for an hour or two, I might very well—wearing my bourgeois clothes—get to see Miss Amanda again." (1.24.49)
Julien knows that a girl named Amanda is interested in spending time with him. And if history holds true, we can assume that the main reason he's interested in seeing this girl is the thought of having sex with her.
"You miserable child! Ten years from now, who knows? It might disgrace you." (1.26.72)
Father Pirard is quick to warn Julien about the risks he runs by keeping a note from a local girl in his trunk. Julien is, after all, attending priest's school. It doesn't look all that great to be sneaking out and trying to have sex with the local girls.
After long hesitation, which an observer might have thought caused by strong distaste—so hard is it for a woman to abandon her sense of what she owes herself, even in yielding to a will equally strong—Mathilde ended by becoming his loving mistress. (2.16.46)
Mathilde hesitates for a long time when Julien tries convincing her to have sex with him. But in the end, Julien's charm wins out and Mathilde consents. The narrator is sure to remind us, though, that Mathilde is just as strong-willed as Julien. Just because she agrees to have sex doesn't mean Julien holds the upper hand in their relationship.
Who could describe Julien's overflowing happiness? Mathilde's was almost as great. (2.19.39)
It's only when Julien and Mathilde admit their love for one another that they both allow themselves to feel true happiness. They've spent a long time playing their love games, and now it's finally time for both of them to own up to what they feel for one another.
He's nothing but a commoner, after all […] His name will always remind me of the greatest mistake of my life. I need to follow, most faithfully, all those popular notions of wisdom, restraint, and honor: a woman has everything to lose, forgetting them. (2.25.37)
Mathilde tends to flip-flop a lot in her opinion about Julien once they've had sex. On the one hand, she thinks that he's a no-good peasant and that having sex with him was the biggest mistake of her life. But ten minutes later, she might feel the complete opposite.
"So Madame de Fervaques has stolen your heart from me… Has she made the same sacrifices for you, as this fatal love swept me into doing?" (2.30.4)
Mathilde doesn't like it when she sees Julien paying a lot of attention to Madame de Fervaques. She wonders whether Madame has had sex with Julien yet. All of this thinking just makes her crazy jealous. But then again, she's the one who told Julien she wanted nothing to do with him.
"Poor and voraciously greedy, this man sought position and reputation by the most consummate hypocrisy, as well as by the seduction of a weak and miserable woman." (2.35.16)
Madame de Rênal's letter to the Marquis de La Mole leaves little doubt about what kind of man Julien Sorel is. She admits to having sex with him and warns the marquis that Julien is only interested in marrying his daughter Mathilde so he can elevate his social status.
"He leaves behind him misery and eternal regret." (2.35.16)
Madame de Rênal closes her letter about Julien by saying that wherever he goes, he tends to leave behind ruined women and a whole bunch of regret. It's her way of saying that Julien just wants to run around having sex with no regard for the wellbeing of the women he sleeps with.