The teacher assigned the class to form groups of two. So your classmate Bachira, wanted to partner up with Isagi.

"Isa-" Bachira's call got cut off when he heard that Isagi will be partnering with Rin instead of him.

Full of sadness, Bachira creeps back to his chair. He sighed, staring at the window. No other person would want to group up with him. He didn't have anyone else.