1. Look at old photos. Ones from back when you first met can be fun, but even better are embarrassing baby photos and the like.
2. For my last birthday my wife bought two of those foam ball shooter guns from Costco. Every once in awhile one of us will come home to table-forts and obstacles, with a loaded ball shooter waiting by the door. I love her, she’s awesome.
3. Do a project together like restoring an old piece of furniture, making your own beer or wine, or writing and illustrating a children’s book. You’ll have the benefit of learning a potentially profitable skill.