I send a message to my girlfriend every day to say good morning. Sometimes she will reply to me early or not. If you girls receive such letters every day,

No, that's your girlfriend. And if one day you don't send it, a few days later, she won't be used to asking why you don't send it or just sending you a good morning. Actually, you can say something else at the same time, such as good morning. It's a beautiful day today. Are you up? Or what I ate this morning, you should remember to eat something good, she may go on.