Well she went away for a while about 2 years ago to visit family and stay with her aunt after her aunts husband died for about a month and about a year after that I got a random message on facebook from some random guy out in that general area she was at at that time saying they were sleeping together during the time she was there but I didn't get it for a year because I never go on facebook

Now in her defense she did tell me she had an ex when we first met that was very stalker obsessive ish so it might just be that but there are other signs too like love life is non existent anymore as shes "never in the mood" for now 3 years straight. Any other questions you might have to provide you best incite please feel free to ask

edit

Thanks to everyone for responses. I know I probably should have emphasized this a little better in the original post but its really not like a toxic relationship, because we get along fine still talk share stuff, go out to dinner ect mess with each other (jokes ect). I kind of only stated the obvious thing that happened and then what I have noticed as the red flags. As I said this has been in my mind for about a year now when I discovered the message and I am just trying to figure out how to address it, because my biggest fear is screwing up something over something fake, a joke whatever it might be