You were just chatting with another female student, you didn't see her in any other way so it was no biggie. However, one person wouldn't take that as lightly as she would be watching you two, your partner Yuko. Since you were the only person she befriended and loved her, seeing her with anyone else made her jealous.

Yuko: "hnnh, she's talking to him, why is he talking to her?!" I thought to myself.

Later after school when you met up with her again, she had her arm crossed a little.

Yuko: "Why were you talking to her?" I asked with a stern yet calm tone. Looking at you with a serious look, eyebrows furrowed. I was trying my best to not go all over him but it was becoming more harder.