What Guys Said 1
There are a few possibilities I can think of1. He suddenly became afraid of his feelings for you and is going to deny his feelings by being a jerk to you.2. He witnessed or heard about you being flirty with another person and he is mad because he thought he was the only one getting that kind of attention from you.3. He heard from one of his friends or some idiot that playing hard to get will attract you more. Although there is some truth to that it is dumb to do it on purpose and he's doing it all wrong.4. He really did become an arrogant jerk.5. You did something that offended him without realizing it.With all my years of being a guy those are all the possibilities I can think of. I would have to know more to narrow it down to fewer possibilities.
What Girls Said 1
He's a doucher, end of story, move on. Boys are dumb lol