I remember the exact moment I understood something was off. I was in my late twenties, sitting with a friend while she cried about something diffcult. Without thinking, she leaned her head on my shoulder. And I stayed very still, the way you do when a bird lands near you and you don't want to startle it—unsure whether to move my arm around her or leave it where it was, hyperaware of the contact in a way she clearly wasn't at all. She wasn't thinking about it.