A girl sent me messages several times a day, telling me about her daily life, but not the second reply. Sometimes I get bored with some things.

According to your description, there are two possibilities:

1. In the eyes of girls, you are a very trustworthy friend, and she wants to share the ups and downs of life with you.

2. Girls like you, but because of shyness or other reasons, they don't choose to express it directly, so they hope to find a topic from the little things in life and chat with you to narrow the distance between you.

If you have feelings for her, then you can try to develop further. If you think you can only be friends, just be friends. Even if she has had feelings for you for a long time, she will let it go.

I hope it works for you.