Accusation of inappropriate touching
I am brand-new here. My father (who lives with me) told me he saw my boyfriend touch my daughter (15 y.o.) inappropriately (grabbed her rear-end). She says she wasn't touched. I know my daughter - and I was standing near her when the "touching" happened. She would have responded visibly; she would have pulled me aside immediately...something. We have a very close and open relationship. She is not sexually active and there is no evidence or pattern of this type of behavior by my boyfriend at all. She told me she feels very safe around him. They do play around affectionately - they are both outgoing that way. But I have never seen any interaction even close to inappropriate. They have never been alone together. She says he has never made her feel uncomfortable.
My daughter's safety and well-being are first priority. My dad could be described as "odd" but he wouldn't just make something up out of thin air. He is very upset and will not talk openly with me about the incident, nor consider that maybe he didn't see what he thought he saw. He thinks my daughter is denying (or ignoring) it because, at her age, girls sometimes "like" special attention from a man (golly-this sounds ludicrous now). I have not spoken to my boyfriend yet, since I feel it's best for me to come to my conclusions before discussing with him. Since I have involved my daughter in the conversation, though, I WILL have to speak with him about this. Before I do, I want a sense of whether I believe he did something wrong or whether there is just a misunderstanding.
Any suggestions how I unscramble this very delicate situation?
Thank you for any tips!