Why did a boy secretly look at me when he clearly refused me?

First of all, he turned you down, which shows that his favor is not enough to make him accept you. As a boy, he really likes you and is timid, which can be seen in many ways. But it doesn't mean that he is timid enough to refuse to be with you and refuse your request.

Then, I stole a look at you, probably because you left a deep impression on him and unconsciously brought some attention.

Finally, why do you say that you don't have much affection? Because you still have a little affection. After reading the reply from a close friend above you, I am telling you that he doesn't hate you.

A boy is a very proud creature. If he really falls in love with you, he is likely to do a lot of things that are not in line with his original behavior, just to make himself less proud for your temporary happiness or not. For example, at a class reunion, he wants to push a cup with others for a change, but as soon as you frown, he immediately puts down the cup.

Maybe his behavior will make other friends laugh at him, but as long as he really loves you, he is willing to put down his dignity for you. At this time, he will think that you are more important than everything in the world.