“Excellent!” Miles said, as if we were going on a macabre amusement ride.

Even though I am not good at mathematics, I found myself ruminating on the cruel geometry of the accident: the driver of the long semi-truck swinging out at a wide angle that unexpectedly narrows, blinding him to Eric’s presence; the rear of the truck breaking the trajectory of the motorcycle’s path as it turned in its respective lane.

There were two impact points: the middle of the truck (his head) then the asphalt 30 feet away (the left side of his body). A hypotenuse of flight. Smashed ribs. Traumatic brain injury. A compound fracture of his left leg. A shattered left arm.

I didn’t want to see him broken.

“Which way to the acute care unit?” I asked the front desk attendant. We followed signs along a circuitous route as my stomach roiled with dread. Visiting at such a vulnerable time, his survival still uncertain, seemed wrong. Like it should be just family, which we weren’t exactly. I didn’t know what my relationship to Eric was.

Like other couples we know in open arrangements, my wife and I compartmentalize, keeping our dating relationships mostly off each other’s radar, a buffer against jealousy and insecurity. To most people, we look like a conventional family: two parents who met in college, three children each spaced two years apart, a pretty four-bedroom brick house.

Close friends and family know the deeper story, but otherwise we keep it to ourselves. I’m careful about how I move in the world because people judge, or they are uncomfortable, or they avoid. This situation — entering the hospital room of my wife’s lover — risked exposing our oddness in a way that unnerved me.

“Elevator six, over there,” Miles said. “Step it up, Dad. The burrito will get cold.”

“I’m pretty sure it’s already cold, buddy.”