Frost and Cinnamon have that "Rivals" to Lovers trope. (Maybe I'll make a comic about the Tiger lore one day- let me know if you are interested!)
Frost was jealous over Cinnamon being appointed as Misty's royal guard*, but this wasn't a regular Yandere jealousy. Oh no, Frost HAD to prove herself the better of the two.
It was an obsession to the highest degree, but Frost couldn't beat Cinnamon's traps! Brute strength? Frost would win in a heartbeat, but these contraptions Cinnamon spends **HOURS** on- they bested her. Every. Time. (They get into many heated debates which Misty has to mediate.)
Frost didn't quite understand her jealousy. It was shown quickly that Cinnamon wasn't a threat to her position. And she shared Misty. So why was Frost so jealous of Cinnamon?! It made no sense!
Then it hit her. She was in LOVE with Cinnamon! She loved the mischievous brat who always knew how to get under her skin! She wasn't jealous of Cinnamon; she was jealous that those stupid machines took Cinnamon's attention away from her!!
With Misty's help, Frost planned to confess. It was a beautiful moonlit night and Frost confessed in a stammering cute way. Just for Cinnamon to say:
"Wait, haven't we been dating the whole time?"
*Check out Frost and Cinnamon's All About Page for more details!