After his divorce my oldest brother stayed with us. What was meant to be temporary, turned into him living with us for the next 7 years.
As of the 2nd week of living with us, he became my wife's regular and long term lover. On weekends with time on our hands we slept all 3 together in our main bedroom, during the week I often stayed in the guest room and my oldest brother slept in my bed.
And as I was often away on business, he took up my place in our bed, bedroom, in my wife and my wife practically led a life with 2 husbands, which made her very happy and she quite visibly seemed to enjoy it a lot.
When my brother moved in, we already had 1 daughter, then aged 3, and when he moved out 7 years later, we had achieved what we always said was our family planning goal, namely 4 lovely and great children, our oldest daughter who turned 10 by then, and then 3 lovely and great boys, aged 6, 4 and 2. I guess we can say that my wife is the natural born mother and my older brother is the natural born breeder, and I am the doting official father, provider and I am always very happy when I get my shoulder slapped and being told what a super stud I am.
But really, I could not be more happy and it was just so lovely to see my wife being lovely big, happy and pregnant and surprisingly the nurses and midwives in the maternity ward did not even bat an eye-lid, when 2 men were sharing the normally exclusive "Dad in the room" role and were very supportive of all of us.
I got very friendly with the head nurse of the maternity ward, and when our last boy was born, we had a one-to-one conversation while waiting for things to happen, and she held my hand, looked me in the eye and said, that it wasn't any of her business but she had been on duty with all the deliveries, and she clearly remembers me being on my own with our first child and then the other three it was me and my older brother.
So I told her. And in the end she hugged me and said that this was so nice and I was a really good man, hearing all that she wished that she would also have been so lucky to have a similar relationship, but it proved to be so difficult to find really open-minded people with whom such a relationship and lifestyle was possible.