Future Ted closes the episode by noting that while no one can vow to be perfect, they can promise to love each other with everything they’ve got, because "love is the best thing we do". The End of the Aisle | How I Met Your Mother Wiki | Fandom

: Barney witnesses Marshall and Lily’s messy, honest life and decides on a single vow: to always be honest with Robin. He immediately confesses that Ted was the one who found the locket. Marshall and Lily’s Real-Life Vows

In a pivotal series moment, Robin attempts to flee the wedding and literally crashes into The Mother.

: Ted reveals he retrieved the locket from Central Park Lake but gives it to Barney so Robin will believe it came from her groom.

Marshall promises to stop shouting at Lily while she is "dropping a deuce".