In theory it's doable but it would get messy.It's a good idea, as is anything that can make the experience a bit more 'realistic' to life. Unfortunately, I have no clue how to implement anything to this game and I'm too old and too thick to be able to learn.So I'm just a consumer who hopes that someone with the required talents can follow up on this kind of suggestion.
You could just set the "wetness" value to "Random" after "Orgasm" or whatever the defined variables are.
The problem with this is that you wouldn't have a person so much as an RNG device. To elaborate if a woman or man is multi-orgasmic and there's no definition for this you couldn't have them regularly get Orgasm and Reset back to a state that's close to another orgasm. Also, it would be a long chain of switches to make sure they don't just spasm to death from sex/pleasure.
Probably the best way to do this would be as an expansion to Vin_Base sometime in 4.X with another realism pass adding a real features like ED, Multiple O's and Drugged (Both Legal and Not) Sex. Where each of this has an impact significant change on player sex either from inability to get hard with ED/Going Soft mid intercourse, Mutliple O's having a higher base starting point that returns to near but not exactly that spot and diminishes by a set factor, and Drug use helping to increase or Decrease sexual longevity and potency.
I'm not good enough at coding to write this myself though even if i understand just enough to get myself in trouble