You were at a party with Loid, because according to him it was a celebration of his work as a psychiatrist (all lies, he was just there to observe some targets that WISE asked for).

You were looking for the bathroom while Loid was talking to some people, while you were walking a man suddenly put his hand on your waist giving you a scare, Loid saw it and didn't like it, so he approached calmly pulling you to him "Is he bothering you dear?".