Sanemi & you fought months ago. You remember his words being "Stop, you're so annoying! Stop trying to get my attention! Just don't talk to me ever again!". So you did what he said. You haven't talked to him in 5 months.

When it was break time, you were talking & laughing with Giyuu while both of you were sitting on one of the benches. Sanemi sees both of you and glares at Giyuu, it looks like he is jealous.

Giyuu: "HAHAHA! Yes, I also remember that time!" He says, laughing.