Your spectator writes their name on a blank card, and THEY lose that card into the pack. They then write their partner's name on a different card, and that card gets lost in the pack as well. You tell your spectator to think back to when they first met their partner and to imagine the two cards finding each other in the pack. Once they have done this, you spread the cards and the same two cards with names are magically found right next to each other. You explain that the cards have found each other, but you want to take things one step further.
The two cards are inserted back into the pack and the deck is shuffled. You then ask your spectator their anniversary date. KEEP IN MIND this is AFTER the two cards have been shuffled into the pack. They tell you the date and you count down that exact number of cards. Your spectator then turns over the next two cards and they are, in fact, the two cards with names written-on by the spectator.
A beautiful effect that will hit home with your spectator or spectators, as it's so personal to THEM.