On Halloween night, our little group of five had agreed to go to a party together.   I arrived in the costume we'd settled on 2 weeks earlier, only to find that I was the only one who didn't match.   My boyfriend explained without a trace of concern, "There were only four vampire costumes. Your nurse costume is just as good."   My younger sister adjusted her delicate lace shawl. "Don't you hate vampire costumes? Stop trying to squeeze in with us."   My eyes stung. Wearing matching vampire costumes had been my idea.   "Nadine, we're already dressed," my boyfriend said lightly. "Don't ruin everyone's night over something this small."   He put an arm around me as we had our tickets checked. Just 3 minutes later, I was at the back of the line again, separated from the others.   My sister sent a video to our group chat. The four of them stood in front of a party display, my boyfriend beaming.   Conrad: All four of us, nice and neat.   The video was quickly deleted, and my sister added a message.   Felicity: Conrad just misspoke, Nadine. Don't read too much into it.   Suddenly, I understood. He hadn't misspoken.   In their minds, our group of five had only ever had room for four.