365 reasons why I love you jar. Both have their own jar and write once a day one thing they love about the other. On their anniversary/birthday/valentine's day/christmas/whatever the occasion, open the jar and read what the other person wrote
A birthday or anniversary # envelope surprise. Put the envelopes in the number of the year of the birthday or year of anniversary. Then add notes or things get can get for them in the envelopes! Doing this for my Husbands and sons next birthday!