Read receipts tell you the message was opened. They don’t tell you what kind of day it landed in.

Seeing that a message was opened tells you one mechanical fact and nothing about the person. It cannot show you that they read it on a bus, in the middle of an argument with their mother, or ten minutes before a test, and those are what actually decided the reply. The silence you are interpreting usually has a cause that has nothing to do with you.

Give it a day before you build a story out of a timestamp. If it keeps nagging, ask them directly rather than running the theory for a week. And if the receipts make you worse, switch them off.