What should I do if I receive a text message from my girlfriend?

It is normal. Everyone has friends of the opposite sex.

She doesn't care about you. Why should she tell you? What she means is to reassure you that she is a measured person. Don't worry, this kind of girlfriend is very good, cherish it. Don't doubt her. If she knows that you doubt her, she will be very sad, and I don't know the consequences!