We can't but we do

This isn't a typical Miraculous book where Ladybug and Chat noir defending Paris from evil once again or Marinette tries to confess to Adrien. In this book, for the first time, we'll be telling the story of a topic not well explored in Miraculous is the Kwami. Why is it that we know so little about them? We only know that Kwami are ancient and can't fall in love (as stated by Tikki).
So why is it that whenever the holders of the Ladybug and Black Cat miraculous meet, they fall in love?! (e.g., Ladybug & Chat Noir, Shabug & Claw Noir,...)
What are Tikki and Plagg hiding from us?