Do Guys not like quiet shy girls?

I like this guy in school but every time I look at him he looks at me (of what I can see) but when he walks towards me he just passes me and goes talk to his friends! I’ve thought about giving him a letter that told him my feelings, but my friends say it’s just to elementary schoolish! And when ever i’m in groups with him I’m very quiet and shy!! And one day, I saw him hanging over this one popular girl with in love eyes, but back in middle school he asked me out and I said “no”. Now hes gone threw two girlfriends!!!Is there something wrong with how I look or how I act? (i’ve never ever had a boyfriend before!!!)