I think my wife is the kind of person that needs something to obsess over.
It is just part of her nature, so instead of trying to fight it, I try to use encouragement and positive reinforcement to guide her in the right direction.
When she got obsessed with exercise, I made her a little home gym in the spare room. A few months later that was done, the gym was sitting unused, and now she was into collecting books. I converted the home gym into a home library, and I even went so far as to get a dehumidifier for the room just because it helps maintain the condition of the books. I have no reason to think she will be into books longer than she was into exercise, but it doesn’t matter, there will always be a use for a dehumidifier in the house. In this part of the country, we more or less keep our air conditioners running for ten or eleven months a year. It is not only very hot much of the time, but also very humid, and thus many homes have an extra dehumidifier in them, just in case. Modern HVAC systems include a dehumidifier in them, so you don’t need to go buy another one… unless you do! Humidity makes the temperatures feel a lot hotter than they actually are, and with a dehumidifier you can change the soggy damp southern heat into a dry midwestern heat. Thanks to that dehumidifier, the library is now the nicest, coolest room in the whole house!