NozoCoco Propaganda (Species Difference, Age Gap, Originally AdultxMinor, Originally AdultxTeen, Originally TeacherxStudent)

While the Nozomi of the current day featured in Otona Precure is an adult, she first met Coco back in Yes! Precure 5, when she was 14 and he was an adult, working as a teacher at her school to keep an eye on her after a fated encounter. She'd end up protecting Coco, and saying what she wanted most in the world was to help Coco's dream of saving his kingdom come true.

Through becoming a Precure, Nozomi would have stereotypical cliché anime couple encounters with Coco, such as him landing on top of her and causing her to blush immensely, or him crawling into her bed in human form to wake her up when her mother walks in - before turning back into his fairy form to hide that he was ever in Nozomi's room.

In a later episode, Nozomi is struggling to study, getting 18% or lower on tests, and failing to retain any attention towards the study group, but seeming excited at a hot air balloon outside, which is when she runs off. Coco is the only person to follow her, taking note that she liked the balloon, he asks if she'd like to run off in that direction to ride it. During their talk, Nozomi opens up, mentioning that she feels like she's useless and can't do anything - Coco gives her an immensely heartwarming talk about how even if she takes longer to retain information she's not interested in, she's smart when it comes to her interests - she's great at making progress with what she likes, and that's not useless.

I haven't seen any GoGo! Yet, but the two reunite and become officially married in Otona, so these two end up a canon couple!

SakaFuu Propaganda (Species Difference, HeroxVillain, Yandere Tropes)

When the villain Fusion was defeated by all the Precure from Futari Wa to Suite Precure, the body split into several pieces and became scattered around Yokohama. On a trip, the Smile Precure join in with the rest in hunting down the pieces of Fusion before he can reform, as that would spell disaster for many of the Precure.

Ayumi Sakagami got to one piece of Fusion first, who she saved from underneath a leaf that was making it hard for him to move and breathe, naming him Fuu. After she saved this piece of Fusion, he decided to protect Ayumi with his life, and morphed into a bracelet on her wrist when needing to hide from the Precure.

Ayumi would take Fuu to shops to look around, and feed him things in her room in secrecy, without her mom knowing. Ayumi asked him to make sure he ate a lot so he could grow big, as that was healthy. Fuu recalled her getting scared at a dog earlier, and... well, he ate. To protect Ayumi, he ate the thing that was scaring her.

As things continued, Fusion got bigger, and they played games together, learning to have a close connection and love each other. That's when an argument broke out between Ayumi and her mom, causing Ayumi to say she hated her mom, she hated her school, and she hated all of Yokohama. Even though the Precure tried to intervene, Fuu's desire to make sure Ayumi was always happy began the destruction of Yokohama, as he attempted to delete every last thing that was hurting this girl he loved so much.

Ayumi realised her mistake, and wanted to get her true feelings across to Fuu - her feelings for Fuu and wanting him to understand her were so strong, it resulted in her transforming into a Precure herself, Cure Echo - She explained her feelings to Fuu, how much she adored him... and Fuu adored her back. Yokohama (and the dog) were all restored, as he realised he was simply making Ayumi sad.