Vandemolen, when I spoke with Dr Waldinger, he had no idea why testosterone works for my POIS.
I think testosterone replacement therapy (TRT) hastens (speeds up) the semen-regeneration process in cases like mine.
I have been POIS-free for 3 years in my opinion because semen now regenerates quickly after ejaculation.
When my regeneration was very slow, my POIS was terrible.
I realize that regeneration-speed and POIS might be associative, not causative.
And I am speaking for my case only. But I do not see a connection between stress and testosterone. TRT has actually made me more anxious, and my doctor has prescribed to counteract the anxiety effect of testosterone for me.