Any time Daby/Davi translates Makoto's inability to admit her true feelings, resulting in the latter's embarrassed blushing.
In Episode 12, when Ira was about to deal the final blow on Mana, the Selfish body he created from Jun's heart freezes and refuses to strike; the boy had so much love and respect for Mana that even when corrupted as a Selfish he could not bear to hurt her.
In episode 13, Alice handing the Royal Yellow rose to Makoto and after being praised for her, Alice was so cute.
Regina slowly starting to see the error of her ways as she interacts more and more with the Precures is this in itself, especially considering her reactions to cute things like Ai-chan seems completely normal for the daughter of an evil overlord who destroyed a kingdom. The crowning moment is in episode 21, when she finally completes her Heel-Face Turn thanks to Mana's kindness. Goes into Tear Jerker territory where she pretty much says she loves Mana and tries to sacrifice herself so Mana can escape from a pit of lava. Mana refuses to let her do this, and it finally completes Regina's Heel-Face Turn, unlocking her power which King Jikochuu sealed away, kick ass and leave the Trump Kingdom.
Youko and Ayumi (Rikka and Mana's mothers) telling baby stories about their daughters in Episode 34. Rikka was a crybaby and Mana was hyper active.
Youko embraces Rikka and tells her how well she has grown up.
Makoto singing her song to Regina in episode 40. This just might be the first time since episodes 21 and 22 that she interacts with Regina on a more positive note.
Also, the other Cures preventing anyone else from interrupting Makoto's song; seeing as they did help write the song, the other Cures want their message to reach out to Regina as well.
In episode 43 after the Monster of the Week erase the drawing made from Aguri, Cure Ace enter in Heroic BSOD and Manly Tears, but Mari stops the bully from Regina and say that that drawing is from the precious child and the love that her put in a drawing never disappear, she wipes her tears and after her hug Cure Ace.
Episode 44: Regina's tsundere-ish remarks about how much she loves Mana is part this and part Funny Moment, mainly because Mana hears all of it. Even more Heartwarming, Regina's eyes revert to blue when she realizes her feeling.
In episode 46, Regina/Marie Ange finally accepts King Jikochuu, who had also been brainwashed by the dark essence, as her father.
Episode 47: Cure Heart has another talk with Regina in the heat of battle, continuing to say that no matter what, the two of them would always be friends and reminds the latter of their promise to talk to Regina's father.
Seeing almost all of sub-characters coming Back for the Finale is cute and heartwarming at the same time. And it's also nice to see them interacting with each other, no matter how odd the combination is. Karuta Queen and MakoPi fanclub's leader hooking up, anyone?
Episode 48: "Go, Mana! I'm here for you!" This is said by the same guy who spends most of his appearances badmouthing Mana, folks.
Regina, Ai-chan, and Cure Ace save a weakened Trump King for good. Shows that even the parts of Marie-Ange who aren't composed of the love for her father still love him.
If you can relate to the Trump King, the scene become doubly heartwarming: you're a pathetic man who sold your soul to the devil, but your daughter won it back for you.
The entire sequence of Mana's future wedding. Everyone is happy and Mana's parents shed Tears of Joy. And as the Call Back to the beginning of the movie, Mana's future self does wear the heirloom wedding dress.
It becomes more heartwarming when one realizes Momota and Yashima are there. They've been in the series since Episode 1, and the movie establishes them as Mana's childhood friends. Seeing them attending Mana's wedding shows how loyal they are to her.