My grandpa suffered from Alzheimer's before his passing and the symptom shown in the movie is similar to his. The letter scene absolutely broke my heart. The girl loved her man so much however she decided to leave because of her guilt. The ending is bittersweet because it was the first time the man said "I love you" but he realised it is possibly the last time the girl would remember (hence probably the reason he did not look too excited when she hugged him). A must watch indeed!
Review of A Moment to Remember
