Thanks travellers!  
I know some people get sketchy about the topic, but I think there is some science we might be able to glean from collecting the anecdotes.  So thank you for sharing.
I did some more digging, and there is some conflicting evidence about ... and people aren't necessarily throwing this info around in full detail. 
Thihkal reports that oral ingestion of a pure harmaline at 150mg made sex difficult, but sex with 5 g of ground syrian rue was pretty good. (lack of sensation)
https://www.erowid.org/l...ne/tihkal/tihkal13.shtmlMoreover, there seems to be some people who do ayahusca and have sex on it; but no specifics on male/female or actual ingredients/dosages.  A few people mention they've done it on pharma, but again, no specs.
https://www.dmt-nexus.me...aspx?g=posts&t=25450Of course there is a large part of sex that is purely psychological;  if you feel strange about it can govern  performance, chemical or not.  Even for healthy psychological adults.  Its just weird because the masculine psychology / physiology;  for women its pretty common to be unable to orgasm or get lubricated if the brain isn't there, yet there is no stigma - its pretty much like "Yeah, if I'm not into it, the body's not going to cooperate."  
Anyway, thanks!