Why is he being short and rude all of a sudden? Please give me advice?

I met a guy online & talked to him there. Then we started texting. We've been texting for a while, but we have yet to meet.
At first he was really attentive & kept the conversation going, and we learned we have a lot in common and things were good.
Then one day he didn't answer all day so I figured although he hasn't done that before, it's normal, he's probably busy. But when he did answer he's seems different, & now that's how it's been the last three days. He doesn't answer for hours, and his responses are short, and some texts are even kinda rude like he doesn't want to talk anymore. So I just leave it be.
He'll just put "okay" or when I ask him something about himself to get things going he'll just put "no/yes, then just "you?".
It's irritating, when he responses that way or when he takes hours to respond, but I don't get overemotional or suffocating or anything.

So I figured he must've just lost interest so I told him "it's okay if he doesn't want to talk anymore, but just let me know so we don't waste each others' time"

Then he responded right away & sent this long text saying no he still likes talking to me & he doesn't want to screw up. he's very attracted to me and he wants to know me more.
& he said he's really sorry he didn't mean to give off the impression that he lost interest.

He seemed sincere when he said that & things went back to normal for a bit, but this was yesterday night, & now he's back to acting the same way, short texts, seeming uninterested, not responding forever, etc. I know I'm not being clingy or say anything when he doesn't respond or anything like that, so I don't know what is wrong all of a sudden.

Now I'm really irritated. Should I just delete his number and forget about him. My friend said guys just do that, but I doesn't make any sense. All thats happening is I'm starting to not like him.
Why do people (guys) always do things like that?
Why is he being short and rude all of a sudden? Please give me advice?
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