Gertrude's maternal treatment of Ophelia. When Ophelia volunteers to read for the queen and she is laughed at, Gertrude acts impressed she can read at all and asks her to stay while dismissing the other ladies. She is sympathetic to Ophelia being bullied by the other ladies and shares that she herself was picked on at the convent where she grew up. When Ophelia discovers the book she's reading for the queen is actually an erotic tale, they both share a giggle over Gertrude's little secret and Ophelia keeps reading for her.
Hamlet and Ophelia's first kiss. She'd left the dance because she felt out of place and Christina was throwing herself at Hamlet, only for Hamlet to follow her out to the gardens to talk to her. After he kisses her, she breaks out into an adorable smile and can't stop grinning even as she walks away.
Hamlet and Ophelia's secret wedding. They both dress in peasant clothing and sneak out into the countryside to be married, getting to spend a few hours not as the Prince of Denmark and a lowborn lady-in-waiting, but as two young people who genuinely love each other.
Horatio's kindness and protectiveness towards Ophelia all through the movie. He never treats her like she's stupid, treacherous or crazy, invites her into the library even though women aren't allowed and although he ships her and Hamlet together, it's never at the expense of her own well-being. He's the one who comes to tell her that her father is dead and stands with her at his funeral. He blatantly lies to keep her safe when she fails to show for her unwanted wedding and has nothing but faith in her when he figures out she's going to fake her own death, digging her up and helping her through the forest.
The final scene revealing that Ophelia escaped Elsinore and survived. We see her smiling and free, playing with her young daughter in the countryside]]. It's even more heartwarming if one believes that the little girl is her daughter with Hamlet, as she still has something of him besides memories.