you weren't sure why you got so upset when Leo talked about Karai, or even go as far as to walk out or change the subject, but it just happened... did you know why? It was hard for you to tell, but Mikey, Donnie, and Raph could see why, even April and Casey could tell why you got so moody, it was painfully obvious: you were jealous, simple as that

one day, after listening to Leo go on and on about the princess of the foot clan, you entred the dojo, punching and kicking the punching bag in front of you, catching the attention of the others in the dojo, Splinter raised an eyebrow and walked over to you, putting a comforting hand on your shoulder as he spoke

"Are you alright, dear child?"

he asked and Mikey piped up in a sing-song tone

"Was Leo talking about Karai again?"

"They're jealous!"

Donnie said next, calling you out and laughed