I didn't answer because I'm not sure what to say. I'm married and my POIS started when I had been married 7 yrs or so.
But what I have noticed, is that POIS seems to be a little less when she is ovulating.
I explain it as that it is hotter, and the orgasms are more complete. I feel that when they are not, there may tend to be some retrograde
flow, which has always been bad for me.
When the penetration is "solid" there are fewer obstructions. When it is weaker, "the path" is not as clean, direct.