Sex as a power tool, human sexuality, romantic relationships (married or otherwise), and adultery are all regular themes of the series.
Chapter 1 (S01E01): A man receives a call on the phone from his girlfriend and she tells him (in crass terms) that she wants him to perform oral sex on her. Later, the same couple is seen having sex in bed. The scene is quite explicit. The woman climaxes loudly and the man climbs off her. We see his bare buttocks and her bare breasts. They put on their underwear and lie in bed talking for the entire scene. He makes a comment about her licking [his] balls.
Chapter 2 (S01E02): Briefly, a topless woman is seen in a mans room while two men are doing drugs. Later in the episode, a woman (a prostitute) is told to receive money by taking it in her mouth. It is vague, but only implied, that she is being paid to be silent and also perform oral sex on the man giving her the money.
Chapter 3 (S01E03): There is comedic, yet mildly explicit, discussion on what a peach-shaped water tower resembles on a woman's anatomy.
Chapter 4 (S01E04): The episode ends with a younger woman inviting an older married man to her apartment for sex. The episode ends on them consenting, but the actual sexual encounter is not shown.
Chapter 5 (S01E05): An older man and a younger woman are seen in bed the morning after a night together. Later in the episode, the younger woman suggests to the older man that he have naked pictures of her on his phone. She disrobes and we see her bare buttocks and a lot of cleavage (but no other nudity, topless or otherwise). She stands before him, sits on her bed telling him to take "pictures I wouldn't want my dad to see", and lies back out of frame. As he takes the pictures he tells her to "be creative".
Chapter 7 (S01E07): An older man performs oral sex on a younger woman while she speaks to her father on the phone. The scene is very intense and goes on for several minutes, but features no explicit nudity.
Chapter 9 (S01E09): An older man has sex with a younger woman. We see thrusting and hear moaning, but no nudity is shown. They are both fully dressed.
Chapter 10 (S01E10): A woman is paid to seduce a political official. She wears a cleavage revealing outfit and brings him to his hotel room. We see them passionately making out/grinding, but both wear their underwear. Also in the same episode, a married woman is stripped by her extra-marital lover. They kiss, but nothing else is shown.
Chapter 11 (S01E11): A woman strips to her underwear in a married mans bedroom. She puts on his wifes clothes, suggests they have sex in their wedding bed, but nothing happens.
Chapter 12 (S01E12):: Topless strippers are seen in the background of a scene. Later, a stripper is seen topless for an entire scene of dialogue.
Chapter 14 (S02E01): A couple is seen having sex in bed. Thrusting and moaning is heard, but no nudity is shown. The woman steps out of bed and into the shower, only her buttocks are seen. Later in the episode, naked pictures of the woman are found and briefly (for roughly 1 second of screen time) she is shown topless and her buttocks are seen as she is in various suggestive positions.
Chapter 16 (S02E03): Briefly, pornographic images are seen on a computer screen as the result of viral pop-up ads.
Chapter 18 (S02E05): Briefly there is an intense scene of autoerotic asphyxiation between three people having sex. A man is bound tightly by rope and has a bag on his head while a woman performs oral sex on him. As a man goes down on him, the woman tears the bag from the first man's head as he climaxes.
Chapter 19 (S02E06):: Extremely briefly (blink and you'll miss it) a woman's nipple is seen in a topless photograph. Later in the episode, a woman grabs a man's crotch and asks, "Do you want to fuck me?" Nothing happens between the two except for that.
Chapter 21 (S02E08): A woman is seen in her underwear for an entire scene, for no real apparent reason other than, naturally, shed be in her underwear when alone. Also in the episode, a lesbian couple are shown making out (although nothing else is seen).
Chapter 23 (S02E10): A man walks in on another man watching pornography, although he is fully clothed and is actually just literally watching it. The images on screen feature woman in underwear, although no nudity or sexual activity is shown.
Chapter 24 (S02E11): A lesbian couple are shown intimate in bed when a man spies through the window. Both of them are naked in their bed making out. One woman sucks the others nipple while fingering her. Also in the episode, a married couple engage a younger man in a threeway. We see the younger man kiss both the wife and then the husband, but nothing else is shown.
Chapter 27 (S03E01): Briefly, a man's naked backside is seen as he climbs into the shower. Later in the episode, the same man buys a sex worker's services and she is seen naked (toplessness and backside) when she helps him out of his clothes.
Chapter 28 (S03E02): A woman climbs atop her husband and rides him. The scene is very brief and non explicit, no nudity is shown.
Chapter 31 (S03E05): Briefly an adult couple is seen having sex under the bedsheets. There is no nudity, but light thrusting is seen and soft moaning is heard.
Chapter 33 (S03E07): A woman invites a man to a party, after which she sleeps with him. We see them kiss, take off their shirts, but no nudity nor the sexual act is shown. They are shown the morning after in a state of undress, but no nudity is shown.
Chapter 34 (S03E08): A man and woman are seen in bed after having slept together. No nudity is shown, but they are in a state of undress.
Chapter 35 (S03E09): The episode opens on a sex scene. We see a woman riding a man and moaning loudly. She comments that she did "cum". We see the couple in the room having a conversation for the remainder of the scene, although the only nudity shown is the man's bare buttocks.
Chapter 38 (S03E12): A man and woman starts to kiss each other passionately and proceed to take each others' clothes off. No nudity is shown as the scene cuts
Chapter 39 (S03E13): A woman asks a man to fuck her violently, they position themselves in bed and the man starts to take off his pants. This is interrupted when the woman asks the man to look her in the eyes. No nudity is shown.