So consciousness and matter are very friendly with one another. They interact all the time. That's one of the most obvious things about our world, yet it's seldom talked about. Science has nothing to say on the subject. Now, here's something else very odd.
Consciousnesses can interact with matter readily enough.
But they don't seem to be able to interact with one another. I'm sure, if it was at all possible, we'd have evolved to do it. But we didn't. So communicating directly conscious self to conscious self must be really difficult, if not impossible. So not being aware of other consciousnesses is no proof they don't exist.