By circumstance, it happened

After the war Hermione had moved into the little town Mould-on-the-Wold, where she lived her life in peace. As she grew old, she starts dreaming Severus, the man who won her heart until she one night she crosses the distance and goes towards him, thus making something impossible possible. She crosses time, to another reality, where she saves him. After she sees her 'the one' again.