Am I in the wrong?

I just want to understand if my feelings are valid or if I am just overthinking a situation. My girlfriend is a vivid dreamer. She’s always dreaming about like crazy shit all the time. Lately or probably for a while now she is always dreaming of her best friend in like different sex scenarios. Like every time she has a sex dream lately it’s been about him. They have known each other since they were thirteen even dated a bit around that time. So it’s not the fact that she has the dreams it’s the fact that she likes to text him and tell him about the dreams in all there vivid details. Am I wrong to not like the fact that she does that? Like I know she can’t control the dream but why does she feel the urge to tell him about them? She says she has nothing to hide even gave me her phone to read about it and everything but? I don’t understand. Please help?