"Shall I schedule these breakdowns in advance? Perhaps two a season, with a curated list for fast recovery? I'll accept a tea blend of your choice, complemented by a stern talking to and post-discussion cuddling." "Don't forget to work in a sweet pastry," Kianthe grinned. "You know. Something you baked beforehand, because we both know I'm terrible at that." Reyna started laughing, and Kianthe joined her [...].

I think this passage perfectly sums up their relationship. They are there for each other, support each other emotionally, and talk openly. They know each other's strengths and weaknesses. And they make each other laugh. I totally get why they are a couple, and could barely imagine either of them with someone else.