Why does a girl always ask me if I want another girl?

First of all, this is a good girl. Secondly, she is attached to you and cares about you. Another point is that her sense of security is not enough. Maybe your negligence will cause a big gap in her heart, and she will think that you don't care about her. You need to pay attention to the details, don't show indifference, and think more about her everywhere.