Under the Apple Tree

Listening to 'Don't Sit Under the Apple Tree' yesterday, it dawned on me how much WW2 popular culture actually articulates an anxiety about infidelity: the whole Brief Encounter vibe. Now, of course this has a practical side to it, for this was a period when a very large number of people were separated from their loved-ones, and of course anxious about what, and with whom, they might be doing. But I wonder if there's a bigger question here, something to do with war, and large-scale mobilisation that involves a sense of bigger 'infidelity'?