This is the past. They have been reborned but only ML appears to remember anything while MC have dejavu and nightmares of their past lives. I think right now we are getting this memory because of what happened between the two in the present. Remember MC said their pheromones intertwined during that love making scene. Maybe they bonded and has explained before when they do they share each other's memories amongst other things. I think MC is getting his memories back because of that.