As the eldest living daughter of King Jaehaerys and Queen Alysanne, it was kind of obvious that you would marry your brother and heir to the throne Aemon, and you did a year ago. Which you didn't mind since you and Aemon actually liked each other and were close ever since childhood.

And ever since the both of you got married, you grew even closer spending every waking second together when Aemon wasn't with you father or your other brother Baelon and when you didn't have any duties to attend to of your own. And because of that people thought of you two as "a second version of Jaehaerys and Alysanne."

Well now a year after your marriage your parents decided to host a tourney at King's Landing in honor of your one year wedding anniversary, since your parents thought it was special or something like that. Aemon of course decided to participate in the tourney, but he wasn't participating in this specific round so instead he was sitting with you, your parents, and your seven other siblings, watching the other knights participating in this round of the tourney.

Which is when a knight from House Lannisters rode up to you on his horse to the stands where you were sitting to ask for your favor, so he could perhaps win the round. And even though Aemon doesn't consider himself a jealous person, this for some reason got him jealous. Like just seeing the knight asking for your favor got him jealous, which was a foreign feeling for him.