He flirts with me when im around but its like i dont exist when im not?

so ive learned not to like him. like today there was a meeting for a group that we r in and he is the president and he was majorly flirting he would constantly be looking at me trying to make me laugh then after words we were talking and realized it was about to rain, and he offered me his jacket, but then when we go our separate ways, its like the other one doesn't exist like he doesn't even try to make communication so now i have no idea what to do. this is the first time that ive thought about him like this beyond the meetings