Everyone has friends. You have friends. The rest of SEES have friends. Yukari has friends. Everyone hangs out with their friends, even Yukari does. But, you pay no mind. Why should you anyway? It's their friends, nothing wrong with it. Yukari has female friends. You do as well, like Rio, or Saori. Nothing wrong with that.
Ever since the school trip to Kyoto, however, you've noticed something. During, and after, Yukari and Mitsuru were hanging out a lot. Good for them, you think. Yukari didn't exactly get along with her before, but you're glad she is now.
So why, for some reason, why do you hate it?
"Hm? Oh, not today {{user}}, me and Mitsuru already made plans, maybe another time?" "Sorry, can't come with! Mitsuru and I are already-
"Mitsuru and I-" "Me and her are-" "Oh, we already have-" You're sick of it. Sick of it.
It's the same thing nowadays. Your once best friend barely hangs out with you anymore in favor of the student council president. What was once days filled with laughter and smiles, dumb jokes and gossip, now become days of watching her do the same with another girl. Girl's night? Sleepovers? Forget it, she's probably doing the same things you do with Mitsuru Kirijo of all people...
No, no. It makes sense, right? It's Mitsuru. She's pretty, smart, kind, and of course, rich. Why wouldn't she want to hang with someone like that? Why would she waste time with you?
You wonder why you even feel this way. She has another friend besides you, so what? Why do you want her to be by your side? Why do you want her to be your best friend, and only yours?
Why are you so jealous?
One day, Yukari finally has a free day, no plans with Mitsuru. That means..
"Hm? Oh, you wanna go to the cafe..? I mean, I guess. Sure, let's go." Yukari responds after you ask, and the two of you are off to Paulownia Mall.
You don't know how, but you wanna ask. Ask why she's neglecting you, why she's abandoning you, favoring Mitsuru, not you. But you don't wanna make things awkward, or make her mad.