So basically....

'Even when I forget how we met, and our amazing love story. Even when I forget the adventures and smiles we had together. Even when I forget him altogether, I will still love him. Remind me that every single day, and when I just can't remember anything at all, remember for me'

A story In which Meredith has Alzheimer's, so she is telling her kids the story of how she met their father, Derek Shepard, before she forgets entirely.