Originally Posted by Sarah_Jayne

If you don't know them well enough to call them friends then you don't know them well enough to know the true dynamic of their relationship. Do you know for sure they don't have some sort of open nature to their relationship? That he doesn't know and has given approval? Do you know for sure he doesn't have any issues that has prevented him from performing and therefore he is allowing her to get that itch scratched elsewhere as long as she comes home to him?

Of course none of that may be the case and she could just be cheating on him outright but unless you call them friends, stay out of it.