Tell me, why do some girls never mention their boyfriends in their circle of friends?

First of all, I live a low-key life and don't like so-called love. Maybe you've seen many female friends' circle of friends are basically one person, with no family and no boyfriend. You even wonder if she has a boyfriend, and then you keep wondering if she is doing well. At present, the psychology of China people is mostly comparative psychology. When you can't get relevant information from a certain way, you will try your best to understand her "unknown" side. In fact, maybe it's just that some girls keep a low profile. She just thinks carefully and doesn't like to expose her so-called feelings and love to everyone. She clearly knows that love and non-love are not obtained by external evaluation, but it is not good to have more judgments from others.