Eloise admits in a private moment with Daphne that she acts like a jerk about marriage because she's scared of having kids. Namely, she recounts the night their mother nearly died having Hyacinth, mere months after they lost their father. She and Daphne were closer at the time, and Daphne tried distracting her from the screaming while singing. Eloise acknowledges that she appreciated Daphne's attempts to comfort her, but she still has nightmares about their mother screaming. This gets Daphne to admit that she remembers that night all too well.
After a season of emotional turmoil, Anthony finally wishes to be seen with Siena in polite society — though he invites her to Daphne's ball, at the last minute she refuses. She's tired of being kept in the shadows and knows she'll never be accepted in Anthony's world; and while it's clearly been an incredibly hard decision for her to make, she's decided to end their relationship and move on while tearfully urging Anthony to do the same.
Simon's entire childhood. His mother died in childbirth and barely got to so much as see her child before dying, and his father outright rejected him for having a stutter. No matter how hard the little boy tried to improve himself and impress his Papa, even excelling in other aspects of life such as academics, the old monster never loved or accepted him due to his simple stutter. In fact, he outright tells him he's a mistake and a stain on his family honor when he was eleven years old. It's devastating to see Simon twisted into an emotionally-remote and self-hating rake because his only parent cared more about his legacy than his own son. He's even willing to destroy his own chance at happiness with a woman who loves him flaws and all... just to spite a man who has since been long dead.
Of course it doesn't stick, but Simon breaking things off with Daphne just as they both start to realize they genuinely care for each other. It's clear he's forcing himself to say things he doesn't believe, out of a real desire to ensure she doesn't harbor anything but disdain for him. He can barely maintain eye contact with her the whole time. They're both left broken, bitter, and saddened by the end of the episode.
While it's still fairly lighthearted in season two, Eloise's Performance Anxiety when she's expected to present herself to the queen is poignant. She stalls on showing her family her outfit because it looks ridiculous, not ladylike at all, and begs her mother to let her get out of her pithy attempts to impress the queen. Much later, when she practices dancing, she's still nervous about the fact that she can't measure up to Daphne's season.
There's something utterly devastating about Anthony's panic attack when Kate is stung by a bee. For all he's railed against it, he is already so much in love with her that the prospect of losing her (the same way he lost his father, as if it wasn't bad enough already!) is enough to utterly wreck him.
Kate's backstory: through no fault of her own, she's the most scandalous item to arrive to London. Her mother, a noblewoman, married a clerk, and by all accounts, they had a happy life in Mumbai. Then her dad died, and his income stream, plus any savings that Mary had, dried up over the years. Kate knows that the queen looks down on her as living proof of what her stepmother fled from London, and her step-grandparents treat her as an annoyance. While the Sheffields will financially support them if Edwina marries a nobleman, Kate doesn't want Edwina to be forced into an arrangement. She wants her little sister to find love and happiness, something she feels she doesn't deserve to have. Lady Danbury has to call out Kate, saying she deserves better than to be a neglected old maid.
Edwina's outrage once she realizes that Kate and Anthony are in love is overshadowed by the sheer pain the girl is in. She has trusted Kate implicitly her whole life, believing everything she does is to help her, and now is faced with what is to her mind absolute betrayal. She's not just spitting mad after she bolts from the altar, she's choking on tears and very close to a nervous breakdown. For her part, Kate can do nothing but stand there and absorb her sister's fury, knowing that she is guilty of it all and the relationship they cherish is forever ruined.
The nadir occurs a few scenes later, when Kate refers to Edwina as "sister" and Edwina immediately snaps back, "Half-sister". The anguish that one word, that single distinction causes Kate is heartbreaking.
Kate's stepmother assuring her that she was never anything less than a full daughter to her, and admitting she shouldn't have let Kate take on all the burdens for their family after her father died.
Kate: You took me in as your own. And you never treated me any differently. Everything I... I did, I owed it to you. Lady Mary: You owed me nothing. Oh... You never had to earn your place in this family. I loved you from the day I met you. Oh, love is not something that is ever owed. You came into my life as a daughter, and I never saw you as anything else. It grieves me to think you do not believe you deserve all of the love in the world.
The flashback to Edmund Bridgerton's death. He dies randomly on a sunny day, stung by a bee while gathering flowers with his son after spending the day together. One moment, everything is bright and happy. The next, he's dying. He's gone within minutes, leaving his son and heavily pregnant wife to watch in horror as their world crashes down around them. Going by his symptoms (a nasty rash developing where he was stung, and severe trouble breathing), it's pretty clear that he had an allergic reaction.
A blink-and-you’ll-miss-it tearjerking detail: The flowers Edmund had stopped to pick when he was stung were hyacinths.
Later, Kate being stung by a bee. She's completely fine, more annoyed than hurt, but Anthony is visibly freaking out, asking if she's alright and clearly terrified someone he knows is going to die in front of him again, the exact way his beloved father did. When Anthony later tells her how Edmund died, Kate is visibly affected when she understands his reaction.
Just the fact that Anthony never got the chance to truly grieve his father before he had to take his place. Immediately after Edmund dies, Anthony is bombarded with the need to make arrangements as the new head of the house. The worst of it is the night that Hyacinth is born, and the doctor tells him that he will have to choose between saving his mother or his sibling. Of course we know that Hyacinth and Violet both make it out fine, but it's gutwrenching to watch Anthony struggle to even speak while his mother screams that Edmund should be there, not him.
The flashback to Violet immediately after Hyacinth's birth. She's nearly catatonic, forcing herself just to keep living day by day. This is what puts Anthony off of the idea of ever marrying someone he loves, terrified that he could inflict such agony on someone if something should happen to him.
Immediately after this flashback, in the present, Anthony goes to visit his father's grave and Violet finds him there. She tries to talk him into marrying for love by citing her marriage to Edmund and how happy it made her...only for Anthony to throw it in her face (albeit calmly) by informing her that her breakdown over his father's death and how much she loved him is why he never wants to marry for love. Her shocked and regretful expression says it all.
In the midst of an already terrible situation at the failed wedding, King George wanders in... thinking it's his and Charlotte's wedding day. Charlotte is obviously devastated, while he affectionately calls her "Lottie" and babbles about how excited he is about the wedding. Some guards come to escort him away, but he fights them and asks why they're doing this, obviously distressed, while Charlotte watches in agony. Luckily, Edwina plays along, showing him kindness and calming him down, before gently persuading him to go and rest.
At one point, Daphne mentions that Anthony never wept over their father's death, despite how traumatic it clearly was for him. Later, when he hears that Kate survived her accident, he finally puts his head in his hands and cries. It feels like a very long time coming.
The confrontation between Eloise and Penelope over the Whistledown papers.
Penelope:[crying] Eloise, I'm sorry. I'm so sorry. You are right about all of it. I was trying to protect you. Eloise: Is that what you were doing?! By writing about me in your latest sheet?! By telling the entire world about things I trusted you with?! Penelope: Only to convince the queen it wasn't you. It was the only way I could save you. Eloise: The only person you were interested in saving was yourself. All so you could keep making money, at a cost to everyone else. At a cost to Miss Thompson. To my brother. To my entire family. To your entire family. I ended my friendship with Theo because of you! One of the only good things in my life, all because of your self-serving manipulation! Penelope: You have no idea how horrible it has felt to keep this from you, from everyone, for so long! Whistledown has been all I have had, and I have given it up. I am done with it. I wrote what I wrote, and I gave it up for you. Eloise: I do not even know you. I look at you now, and all I feel is pity for you. Sequestered here in this very room, writing your secret little scandal sheet, tarnishing everyone in town because you are too scared to stand up for yourself in reality. You are something, Penelope. An insipid wallflower, indeed. [walks to the door] Penelope: At least I did something. All you ever do is talk about doing something. You've all these great ambitions, these great plans, but I am the one who did something great, and you cannot stand it, can you?! And what do you think that makes you? Eloise: I wish never to see or speak to you again.
