Whilst loath to bring torah to a forum, I must suggest something to those who say there is no Mekor for an anniversary. those involved in the “Seforim” will know that each day has its hashpo’o Milmaalah (see Berditcherver on I think Chanukah about why certain Nissim are celebrated and others not, see Maharal about Roch Chodesh Nissan, See Ohr gedalyohu on the same). Now, while it may be arguable that these hashpo’os always existed and our anniversaries do not affect this, I would say (only guessing but based on knowledge of above) that an anniversaries are a prime time to relate to the hashpo’o that existed on one’s wedding day and reunite under the Chuppah.
Bit flowery I know 🙂
you see Joseph, one can know a little Torah and still be happy 🙂