Keeping His Options Open

I went on a date to a concert with this guy once. When he came to pick me up, there was a girl sitting in the front seat. I just assumed she was a sister or cousin.
He never introduced me to her, so I decided to say hi when he went to the bathroom. She was his other date, who happened to think I was the cousin/sister. So we confronted him, to which he said, “I didn’t know who I like more yet…” We left and shared a cab home.