Why does this shy guy avoid me?

Some 3-4 months ago I noticed this really cute guy whom I caught staring at me a few too many times, he used to look away when I looked at him. After a week or two I decided to initiate a conversation with him and his group of friends, it was the day before my birthday. Our conversation was simple with me complementing how good his glasses look on him and asking about his interest in drawing, he seemed a bit awkward and that's when I realised that he's actually quite shy. I became good friends with his group of friends but since then he started avoiding me. Despite knowing my birthday he did not come up to me to wish me unlike his group of friends (now my friends too). His friends somehow found out about my interest in him and casual teasing began. But his behavior became weirder day by day. He avoided eye contact as much as he could, sometimes hid behind his mates while walking from the same street as me, turned his back if I was around. Every time I asked him something (which was barely once or twice) his response used to be quick and one worded, he would look everywhere in the room but at me. He sometimes talks to my friends. Three months later, I decided to confess my feelings to him over text, when I texted him saying that it was me, he quickly responded. So I asked him if he was free and that I had something to say. He cut me off with "studying right now, ttyl", he did not ask anything about how I got his number. The next day I went up to him and he asked me what I had to say. I couldn't confess so I left and did it on text after I got home. He quickly responded with "Friends. Nm". Since then he has stopped avoiding me but tries to act a bit rude which is weird since everyone says he's the nicest and most sincere guy around. He seems pretty casual at talking to other girls. I texted him again and he responded with 'busy in class'. what's going on in his mind? Does he dislike me for some reason? what should I do? How can I get him Talking?
Why does this shy guy avoid me?
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