A girl didn't see my text message for the first time, but she didn't reply to me after seeing it. What does this mean?

This question is complicated and simple. It seems to be a girl you like. Because you don't know much about her personality, it's hard to say why she did it. There are many external factors. If you really like her, don't mind and don't mention it to her, just pretend it never happened. Come on, man, catch up!