Until This Moment
The Indestructible Soul was a rare phenomenon of the martial world. In fact, it was so rare that Ryu didn't know much about it outside of its base abilities. Seeing it interact with the souls of Yaana and Ailsa, though, he found it all to be very fascinating.
The gap between his soul and Ailsa's was enormous. When they dual cultivated, it should have been her nurturing his soul, not the other way around. But, somehow, the exact opposite occurred.
Beneath the influence of Ryu's Indestructible Soul, both of his wives found their souls growing in foundation and gaining tinges of gold. Though it didn't seem like there was any amount of sex that could bring them to the same level as Ryu, what was undeniable was the fact that the stronger Ryu's own soul grew, the more they would benefit from it.
These benefits were fairly subtle for now. But, Ryu had a feeling that it would be a great help toward the two women forming their Godhoods in the future.