Two friends telling conflicting stories

First of all, it’s none of my business but I don’t like it when I can’t figure out who is lying. I have an older male friend at work, and an older female friend who has retired. Both of them know each other. There is a younger woman at work who I noticed always pays attention to me and my guy friend. She is the niece in law of the older woman I’m friends with. I heard from my lady friend that my guy friend once sent the younger woman flirty emails because she held the door open for him once and smiled at him. My guy friend doesn’t know I was told this. One time the younger woman saw my guy friend in the hallway and asked him where his friends were, meaning me and others. My guy friend told me this because he had been looking for us. He maintains he doesn’t know the woman’s name. So who is lying?

My guy friend and the younger woman must be known to each other somehow if she felt comfortable asking him where his friends are. They also seem aware of each other in the cafeteria