He wanted to hook up with you that's why he was nice to you. Would you "love" him or hang out with him if he was nasty to you? Jerks can be nice when they want to be. But its false (acting)! A few nice acts doesn't make a nice guy. Its called manipulation, Barbie and its one of the lessons that a nice (but naive) girl like you need to learn. There are some GENUINELY NICE GUYS around but there are also plenty of ****S WHO KNOW HOW TO BE NICE WHEN THEY WANT.
Ask yourself when judging a guy is he mostly nice but messes up sometimes or is he nasty but nice when he wants.
ASSHOLES that are nice SOMETIMES are not being NICE TO YOU they are being NICE TO THEMSELVES.