Why do some people always fail to reply to others' short messages in time?

If it's not because I'm busy ... that means I don't care about you, I don't like you, I don't want you to disturb him, I don't want you to appear in his life, I don't want to have anything to do with you, it's as simple as that, I may say it tactfully, which will make you sad, and there's nothing I can do. I just want to tell you that this is the truth. If it's a lover, it's really boring. Let's leave early.