The Mother died. We learn Tracy got sick (the "vital biological process" foreshadowed by her ex-boyfriend’s death). And Ted, after six years of mourning, rushes to Robin’s apartment... holding the blue French horn.

The timeline catches up to the framing device of the show. Sitting on the couch, Ted's kids call him out. They point out that his massive story wasn't actually about how he met their mother; it was a story about how much he loves "Aunt Robin". With his children's explicit blessings to move on six years after Tracy's passing, Ted races to Robin’s apartment, standing beneath her window holding the iconic blue French horn .