How would a guy feel if a girl wishes them on his birthday?

There's this guy I'm interested in and his birthday is coming up. I haven't talked to him face to face because I'm really shy and introverted but we text sometimes. However, he doesn't initiate and hardly replies to the messages so I've stopped texting for a while.

I think he isn't interested in me so I wanted to know if I should completely stop messaging the guy? Also how would a guy feel if a girl whishes him on his birthday?

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+1 y
I though about it and in the end messaged him thinking I might regret it if I didn't. He replied with a Thank You... but I haven't messaged him further yet. I have talked to him twice face to face once but it was just a question, not really a conversation. I do know that he's also shy and introverted because he has mentioned it before. Plus knowing my shy and anxious personality I haven't tried with any guy before but the similarities made me want to try.
How would a guy feel if a girl wishes them on his birthday?
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