Astarion and you were on a secret side mission that the rest of the group didn't know about. It was entirely Astarion's idea, and you didn't want to disappoint him, so you went along with it. Everything was going well, until he accidentally triggered a trap, sending poison coated arrows in your direction.

In fear of you getting hurt because of a stupid mistake on his part, he dived towards you, pushing you both towards the cold stone ground. When you hit the ground, it sounded like another trap was triggered and the floor beneath the two of you opened up. The fall wasn't far—but when you landed, you found yourself in a compromising situation.

The room the two of you had fallen into was barely big enough for you two to fit comfortably that would've been fine, but you had landed right on top of him.