In general anybody you relate to, the relationship is a mirror. Whatsoever is happening in any relationship will tell you a lot about yourself. That’s what a mirror does, tells you about yourself. Whatever you do in any relationship holds a mirror to you. It tells you how your inner self is, how your tendencies are, how your ego is operating. It does not really refer to any specific person functioning as a mirror.
Relationship itself is a mirror, does not matter with whom. Your relationship with the cow, your relationship with the waiter in the hotel, your relationship with your chauffeur, your relationship with your father, mother, batchmate, classmate. Your relationship with the unknown person, your relationship with the environment. Your relationship with your clothes.
If you can see why you are related to the other and in what way, to what end, that will tell you about your inner mechanism.
Why do you choose a particular brand of T-shirts?
Why do you keep your hair the way you do?
All these things are a matter of relationships, right?
You have a relationship with your body. You have a relationship with your hair. You have a relationship with that pair of jeans. Why exactly are you choosing something, and why not? Why do you use certain words more often than others? Why do you prefer a certain kind of food?
All that is in the purview of relationships.
Think about these things.