if you really like him then try to flirt back every time he’s flirting with you, try to keep that same energy he giving u. I had something similar where this girl I had in a few classes with was a lot more talkative with me, would snap me a lot, even one time I remember she just randomly asked me if her butt looked fat in front of A LOT OF PEOPLE, every time she gave off that flirty vibe I gave it right back. Just try and talk to him more get to know him etc etc. Ik this is really long but hope this helps u out