Could the levels be depleted by behaviour somehow?
Such as porn abuse?
Did you check adrenal function? In compulsive masturbators, the system is fine but the head’s wrong and eventually the glands pack up and give up.
The masturbators are not actually frigid, although their nervous system might be damaged with time. The idea that looping any addictive behaviour is fine for your health is Peak Boomer.
And by Jove, that title. It’s so true it’s painful.
The butthurt it shall produce, I should buy shares in painkillers.