Why does it mean when he ignores your texts, and when I ignore his messages he questions about it or gets mad?

I've met this guy who I like online, we made a great connection and started talking through text. He's a good guy but honestly he's kind of dull through texting, really short responses. Sometimes he leaves me on read and I do get kind of sad about it but I don't really tell him about it just to not seem desperate. So I wait, when he texts, I answer as soon as I can even when I'm busy. But there these times that I leave him on read and he questions it or gets mad. I want to know why this behavior occurs. Has this happened to any of you girls? Also I forgot to mention that those cute good morning texts sometimes he sends them and I answer them, but when I send them to him he doesn't respond and when he does he just sends "wyd?"
Why does it mean when he ignores your texts, and when I ignore his messages he questions about it or gets mad?
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