Whenever I'm with a friend or a in a group setting, the person talking defaults to making eye contact with other people, but not *me*, specifically. Why?

Please don't tell me that I'm just imagining it, because (a) my hyper-aware friend has also noticed that, and (b) I've noticed the pattern for several years now. It's not as if people avert their gaze when I am specifically talking to them. Strangers are typically nice to me, and I have no trouble maintaining eye contact with them. But 95% of the time that I'm with a friend, or in a group setting, if we talk to a stranger or someone I don't personally know that person defaults to looking at my friend/other people.

For example, yesterday, when I was looking at apartments with my friend, we were both applicants, I had been the one to make the bookings too, so I should've been the point of contact anyway, but the agents kept making eye-contact with HER when they were explaining things. It's not as if she was even more talkative/inquisitive, I was asking questions too, I was looking at them the entire time, they'd answer me and then revert to looking at her.

This has happened in other circumstances too - at professional events, social events, when chatting with a random old lady, etc. I'm considered attractive enough - nothing extraordinary, but I am usually well-kempt and pretty looking. I'm also well-liked by people who do get to know me, and I don't have this issue when I'm talking to people one-on-one, or in a setting when I know the people well.

And people do this "default" no-eye-contact-with-me-specifically thing regardless of who I'm with. I could be accompanied by men, women, non-binary people, plain looking people, loud looking people, etc. I'm truly never the person who gets chosen as the one they make eye-contact with. It's almost like they feel uncomfortable or unsettled by me? Like my gaze is too intense (I try not to stare), or like something's just...off about me and people pick up on that?