My girlfriend told me she was with a friend, but I heard male voices in the background and now I feel like a dick for even caring?

I (M) and my girlfriend (F) have been dating for 3 years now. She's the best thing that ever happened to me, we've never had problems aside from this one. She's on a trip to visit her family, she does this every year around this time. And she told me that tonight she was going to a friends' house. Everything is fine except I know that friend is a guy and his dad is away on a trip. I know this is the friend because we've talked about him before. I don't want to be that guy that is controlling but now I'm overthinking everything. We had a video call and she told me she was at a friends' house but the screen was just her. I know I might be overreacting but now I'm feeling really insecure. After the call I heard a male voice saying "who is this?" I know it's the guy but I don't wanna be paranoid. How can I overcome this feeling of uncertainty?