If he is in the wrong why won't he reply to me now?

almost one year ago I met this guy online and things haven't always been easy between us. about three weeks ago me and him got into a fight and he called me a hoe, the next day he texted me saying "I'm sorry" and ever since he hasn't said a word. I texted him once saying the things he said were hurtful and today is his birthday so I once again texted him "happy birthday, have a happy day. beso" he read the message and didn't even say thank you. why do you think is that?
If he is in the wrong why won't he reply to me now?
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