End of the Line

When Kerry's husband finds out he's going to be spending several hours on a train, he asks her to break the monotony by sending him sexy text messages. She does this and finds herself enjoying them much more than she'd expected to. She reveals fantasies they'd never spoken about face to face. But then he calls to announce he's lost his mobile phone. Does this mean she's been sharing sex-filled texts with a stranger, or is he actually trying to see how she reacts to the possibility it's someone else?