Why did he get offended that I didn’t let him open the door for me?

I was walking in the gym the other day. There’s two doors to it both open outward. As I was walking in I saw a guy coming out he saw me too, he picked up his pace a little to meet me at the door. It seems he was opening it for me but I just opened the other door and went in, I don’t expect men to open doors for me so I wasn’t going to stand there waiting.

But what was weird was he just stood there staring at me after the fact. He looked so offended. I don’t know if he was angry or what but why’d he do this?

Why did he get offended that I didn’t let him open the door for me?
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