mary says she decided to try to make things work with her husband. keithlfriend. >> we both just kind of said good luck to each other. >> so, it was like a handshake and good-bye, huh? >> pretty much. yeah. >> reporter: but a couple of years later, mary says, her marriage was once again coming undone. in the spring of 2012, she tried to friend keith on facebook. he didn't accept the request, but her a message. >> he sent me a message back asking me how i was and i told him that i wasn't happy. and things weren't going too well. >> reporter: she says they started calling each other on the occasional evening. keith, struggling with his relationship, and mary, lonely in her's, confided in each other. was that something nice in your life at that time, mary? >> yes. >> what was it doing for you? >> a piece of happiness, like i felt a little more fulfilled. >> reporter: but she says their phone conversations did, at times, get sexual. was it hi, how are you but did it also get a little steamy, mary? >> yes. >> reporter: still, it hardly seemed like a big-deal re