You don’t have to treat others as if they weren’t there. Of course they’re there. Taking up space, just like like the cat, like the tree in your front yard, like you.
The world is full of others. You can acknowledge them, allow them their sovereign space. But you don’t have to pay attention to them.
Unless you want to. Do you want to?
It’s remarkable what vanishes when we withdraw our attention from it. And what flourishes when we focus.