As our personal experience which might fit here, my wife Snack have a condition wich prevent her for having children, it is not 0 but almost non existant.
Nobody knows in our family or around us, and when somoene ask us why are we not having a baby, i usually blame myself beeing still trying and protect her in a certain way.
So it is mostly shooting free when she is with her lovers.
We eventually met one that have that same fetish, which is a very kind black guy.
He became a big regular of her.
We progressively felt close enough to him to be able to openly share our situation.
And since then we have a kind of special relation with him, different from her other lovers.
He usually cum in my wife as far inside her as possible and love to hold her legs up and massage her tummy in an upward motion.
She loves it and they usually spend a long moment doing it, it his a very special and bonding moment for her, him, and me.to witness.
As he usually stay the whole night or day when we meet he have more than one occasion to do so.
I usually take my turn at the very end or their session when they are all done.
She is usually still quite loosen up and slippery to allow me to slide in without pushing out his cum out of her and let me drop mine somewhere.
We deeply enjoy this all 3 together, we both talked a lot and we would absolutely carry the pregnancy if it ever happend, i always say the mind always play a part too, and if my wife and i really wants it, it can help.