The Alchemists had an idea on this. In order to test if something is “real” you need to leave it someplace for an extended period of time. When you come back, if it’s still the same as when you left it, that means it’s “real”.

You ever have a friend, maybe a best friend, where you would hang out with a lot but there would occasionally be some long gaps between seeing each other, but when you get back together it feels like you never left? You could almost say your friendship is still the same as when you left it.

But to your point, you define what a “friend” is differently. To you, and “friend” is sometime you physically see a lot. So if someone doesn’t see you much, then you don’t consider them a friend. I just define what a “friend” is differently than you. I do not require constant physical contact to consider someone a friend.