Before we started doing the hot wife thing, KK and I did lots of pillow-talk / role-play sessions. She regularly travels for business, has since we've been married - the getting fucked on a business trip scenario was one of my pillow-talk "go-to" scenes. KK's first realistic dildo was acquired for this purpose - she even named it, "Brad," after a guy she worked with that she found hot...
There was a downside to this - while KK responded positively every time I played out the fantasy to her, cumming explosively, writhing in bed like an animal, she always told me after, "It'll never happen." What I didn't know at the time is that she was actually acting on these fantasies during travel - cheating on me - it went on for about two years like that. Eventually, she confessed the whole thing, but in dribs and drabs.