I found this in a catalogue of Victoriana but it seems totally modern and potentially quite useful to me:
Lover’s Quarrel Frame
Photography was once reserved only for the affluent. Given the exorbitant costs of portrait photography in the late 1800s, it was unthinkable to discard a valuable photograph due to a broken relationship. Rather, the undesirable subject would simply be folded back or scissored off. The slender frame which found the height of its popularity after 1910, later came to be known as a ‘Dear John Frame’, thus accommodating the lonely heart beautifully. $16.95
While it pains my romance writer’s heart to say so, I can think of several friends who might find it very appealing.