The Ex at the party: A confusing Encounter

"I was at some party, not sure whose, and he was just there across the room, my ex, wearing a jacket I'd never seen him in. He walked over like no time had passed at all, easy and casual, and I felt myself slipping right back into the old rhythm even though some part of me kept whispering that this wasn't right. We were talking about nothing, his new job maybe, or a trip, and I couldn't tell if I was supposed to be angry or happy to see him. I kept waiting for the awkward part, the apology, any acknowledgement, but it never came. He just kept smiling like it was all normal. Then we were in a car, him driving, and I didn't remember getting in. Streets looked like my old neighborhood but rearranged. I tried to ask why we were even together again and the words came out sideways, something about groceries. He turned to say something and I woke up before I heard it, lying there trying to work out why my chest felt so strange."