I had a dozen tanks when we married, so my wife came into this with her eyes open. But there are a few pointers that I do follow.
1. Tanks do not dominate the area where they live. If the room is smallish, don't go overboard on tank size. Nor does the tank lighting dominate the room - too bright lights can kill the calm of a room and definitely makes the tank dominate the area.
2. Keep the glasses clean. It as amazing how this boosts the acceptance factor of a tank,
3. Never leave buckets, hoses, towels, gravel, test kits, filter media, etc. laying about. this a close corollary of #2. If you are neat around the tank, the tank is more acceptable. If you need the kichen sink for tank cleaning, don;t schedule this when you spouse is sheduled to be preparing for a party.
3b. Plan ahead. If necessary, when planing a tank, make sure you negociate a storage area to be used for all the items listed in #3 and a few more. The storage cabinet or closet is best tank-only, if this is at all possible. Shared storage with household cleaning supplies is IME dangerous.
4. Allow your significant other the reciprocal allowances - if have have tank space in living areas of the home, the SO can have comparable hobby space and funds, but under the same guidelines.
5. Scheme and plan. A tank room/hobby room is the best solution. It likely will not be instant gratification. but it allows storage and space which is not living area in the spouse's usual sense of the word. It is worth planning ahead.