Why would a guy seem interested in person but then leave me on read?

So I met this guy in my program and we hit it off after he asked in our class group chat if anyone wanted to study and I replied. We did like 10 mins of school stuff then we spent the rest of the time talking and getting to know each other.
I told him I'd text him outside of the group chat which was in WhatsApp, and he asked for my number to text in iMessage. We ended up spending a few more minutes together in the library bc I had to print something and he came with me. When I got home, I sent him some stuff from the class and he replied thanking me. Nothing else was said after and I was starting to miss talking to him, so I texted him a question about something someone said in the WhatsApp gc. He read is a minute later and I saw on WhatsApp that he was last active right after he saw my message, which means he went to check what I was talking about but he never responded. I kinda feel down that he left me on read and I'm questioning our whole interaction after class. I thought we were feeling each other but now I don't even know. Can someone help me make sense of this?
Updates
3 d
He ignored me the next time we had class, so I ignored him the following day but he was nice to me and did small things like offering me stuff to borrow for class when I didn’t even ask and then answering questions I was asking my friend. We did a group project and I was in a group with him and he was acting normal, even making jokes and we talked about school and stuff. After class I texted him I thought he’d been mad at me. He apologized and said he wasn’t, that he was just stressed.
Updates
3 d
He’s a really good guy and I like him a lot but our program is demanding asf so I get it. We’ll see how things progress.
Why would a guy seem interested in person but then leave me on read?
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