Well my wife sometimes can surprise me in a positive way.
Following happened some years ago ... and I'm glad it did
Wife and I often went to public (nude) sauna centers and nude beaches, as did her sister with her husband.
BUT, we never went together. Sister in law thought it was weird and awkward that her sister's husband would see her naked and vice versa. But my wife had seen her sister's husband naked already on a few occasions.
So one day, the 4 of us were on a weekend trip, mostly hiking all day.
When returning to the cabin, the girls went into the sauna ... and afterwards the guys.
When we got out, we were still sweating ... the fact that the stove was burning fiercely didn't help with that.
So both of us guys shed our bathrobes and walked around naked.
That was the 1st time my sister in law got to see me naked.
After that, we started playing a bord game. Us guys still naked, both sister's wearing their PJ's, including bra and knickers. Till suddenly my wife said : "After that sauna, it is really too hot to wear clothes ... I'm shedding them too"
Now I suspected that she would just shed the blouse of her PJ, maybe the bottoms, but to my surprise,
she not only shed the blouse, bottoms but she also unhooked her bra and took it off.
So there she was proudly showing her breasts for the 1st time to my brother in law.
Then 3 pair of eyes were looking at my sister in law, but she kept all of her clothes on.
Later that weekend, my wife apparently had spoken to her sister and they both arranged for the 4 of us to go to a sauna together. So we all got to see each other naked a few weeks later ... and have seen each other naked on regular basis ever since.