Sometimes I text my girlfriend, but she doesn't reply. What happened?

This is a matter of personal preference. Maybe she saw the message and understood the meaning. She doesn't think the reply is important. She doesn't have the same emphasis as you. You value such information. And she doesn't really care. But that doesn't mean she doesn't like you. I'm just not used to returning such news, so don't lose your temper because of these little things. It is often so easy to affect feelings. Talk to her more ... or maybe she's too embarrassed to answer your sweet words. ....