i get it, he was having fun messing with her coz he knew she was trying to seduce him and distract him so he messed with her with all the request thinking that she would give up eventually, but she didnt and moment she collapsed it stopped being funny for him specially after she said that part about sticking to the end, he then realized she wouldnt stop so he had to cut off the fake relationship and the guilt of overcharging her probably got him and thats why his grades fell down....
ok now time to read the next chapter and probably eat my fucking words