My girlfriend and I have been dating for 3 years now I have never had any reason to believe she was cheating or doing anything behind my back she’s not secretive about anything. I know her phone passcode she leaves her phone lying around all the time notifications up with volume up I have plenty of opportunities to go through her phone but just don’t. The other day she got a new phone transfered her stuff to the new one and had her old phone on our kitchen table again not hiding it or anything. I was sitting there eating something and opened it up first text her and her best friend I didn’t want to read their conversations or anything but for some reason opened photos they’ve sent eachother. It was a little way down so probably a few weeks ago maybe a month or 2 idk one of them sent a picture to the other of a guys body no face he was in good shape tattoos holding a towel in front of himself where you could just see the start of his dic. We’ve been dating 3 years and her friend is married her friend used to be kind of slutty back in the day I guess so 1 maybe it was old 2 they’re both attractive maybe some guy randomly sent it to one of them the guys phone looked old so maybe an old picture? But it makes me wonder if it’s old why would one of them hang onto it and also why were they even talking about it sending it to the other? The only way I’d be able to bring it up is if I said I checked her phone but we don’t really fight or argue I don’t want to start something if it’s nothing but it’s been on my mind a lot lately. Any advice is appreciated and yes I know shouldn’t have even looked at her phone as far as I know she doesn’t look at mine.