What do you mean when a girl sends a text message to a boy and doesn't reply?

He is playing hard to get, making you think about her all the time, why don't you come back, what she is busy with and what she is doing. Which means she's still interested in you. So there is no need to give up. You played hard to get with her, too. If she is upset, she will take the initiative to talk to you, indicating that she has you in her heart. If she doesn't respond to your indifference, you should think about it.