Same thing is happening to me for the first time. I have Twallan's Woohooer, and still the problem is there. Only, it's just one of my sims who has this problem. He can Woohoo in elevators, in rabbitholes -man, that sounded nasty- and can woohoo if another sim starts the interaction, but when he does it, it can't happen. When they are standing up, find each other irresistible and the problematic sim begins the woohoo interaction, they just freeze in place until I use resetsim. When they are in bed, the other sim always refuses, but if it's her who begins the interaction, no problem. I'm beginning to think other sims just find this one too repulsive, and will only woohoo with him if they have made up their minds to, I don't know, throw him a pity woohoo or something.

I don't know if people keep having this problem. I tried removing the mods that I had installed before this glitch appeared and cleaning the cache and it didn't fixed it. Then I tried selecting a new active household, in the same game, and those sims had no problem... performing. Then I made a new household with sims that didn't knew each other and made that one the active, and again, no problem performing. I tried reinstalling the mods I had removed, giving them to the other households, no problems. So, at this moment, it seems it's only that one sim who has the problem, more and more I believe it's something wrong with him alone, but can't figure what. Hopefully the problem does not spread, if it doesn't, then this might be an interesting aspect to play, a sim that can only get any, if its others who offer.

You see, a vast majority of people think of such activity (and its variations) as a form of love expression, a recreation, an entertainment, and much more, before it is a mean for reproduction. Don't deny such thing from your sims!

Thought I just want to point that out, don't hate me

Well, this bug has made me turn the sim suffering from it, into some sort of monk, he now has an "elevator daughter" -the only way he could have descendants was by using the try for baby option on the elevators, so that's what I did-, and has divorced and retired to a life of solitude and contemplation.
And, I'm thinking this could actually have to do with the fact the sim suffering from this was a fat sim, with neurotic, loner and couch potato traits -also book worm and artistic, but I'm guessing the former ones would have more impact in his sex life-. I just made another one, a muscular beast with brave, athletic and adventurous traits -also book worm and genius-, and that one has no problem seducing half of Bridgeport. So either the bug was only happening on the save game of the fat sim, or this game is more like real life than I had expected.

I don't know what to tell you. Twallan's Woohooer makes even nuns and monks woohoo instantly right after they finish their "Introduction" ritual. Woohooer checks for almost nothing when making 2 sims woohoo (well, maybe age, you can't make anyone below Teen woohoo).

Have you updated Woohooer? Because seriously there is no need to worry about seduction or what so ever with Woohooer. You mention you have Woohooer in several replies above. So I assume you still use it. The only time woohooer fails is when there is absolutely nothing for sims to woohoo on. Unlike RL, sims require elevator or double bed to woohoo on. I never saw sims doing it in rabbit holes so I can't say. Also, Woohooer will direct sims to hot tub as well but (confirmed by Twallan) the woohoo interaction will not initiate in hot tub.

Regarding attraction and such, I notice some sims have mysteriously set their own attraction gauge leaning toward a gender upon creation. I created a brand new household of "3 hot girls" for this sim to date. Everything I did remotely related to flirting returned negative reactions, even one of the girl is "Easily impressed". I used Master Controller to check and these "3 hot girls" had Male preference in -80 (female in +40), which essentially made them lesbians. And just created them 2 sim days ago.

So I may believe that it is either your active sim or the sims he tried to advance on have wrong gender preference. It is hard to tell for sure unless you have Master Controller. So you may have a homosexual sim at hand or the girls he hits on are homosexual. I don't mean this as a joke either.

that damned abstinence pledge is a tricky one, but a roofie should help speed things along.

Wrong gender preference? But it feels so right.

Flirts can change gender preference. Perhaps your sims had a few negative male interactions and then flirted with females successfully (when you weren't looking) - or, if you have twallan's story progression, they could have been randomly assigned to being gay. It might require a better relationship for sims to accept the flirt, but from my experience, they'll eventually accept it. Most of my sims flirt and marry same-sex sims, and recently I just had my female sim flirt with a female sim married to a male. Normally I avoid affairs and home-wreckers (the single exception being a romance sim in sims 2 with a want to woohoo with 20 sims), but she was just so . . . pretty. I WANTED HER GENES.

No I don't have SP turned on or use Twallan's SP. Yes, sims are a lot forgiving when it comes to homosexuality in TS3. But seriously, for the "3 hot girls" household, they don't exist that long to hate male that much (Male preference - 80). If you count in sleep, eat, and getting used to their new place, 2 sim days is nothing, and can't possibly cause them to hate male.

Let's not discuss sexual preference outside TS3, you will open up a lot of ... heated debates.

It's not that they hate the male sims. If your sim is fighting with sims a lot, it's probably dependent on their trait and/or mood. It's just a preference for sexual attraction. The greater the number, the stronger the attraction. Having a +1 attraction for females and -1 attraction for males is not as strong of an attraction of +50 for females and -30 for males to females.

For example, my main sim, who has so far only wooed females, has a male prefewrence of -103 and a female preference of +206. The woman she had a baby with, who was once married to a man (and had a child with him), currently has scores of -60 for males and +117 for females.

And she didn't turn down a woohoo with my female sim after lots of romantic interactions.

The point is, if a sim will make out with another sim, but won't woohoo, that's something beyond gender preference.

Sigh, when I said "hate" I meant having, or causing Male gender preference into the negative. And no, in that 2 sim days they couldn't have done anything related to arguing or whatnot, thus, the gender preference has been given an initial value upon creation of the household, without us users knowing.

Sims show negative reaction toward flirt = may cause by either too strong of an advancement (like attempting to kiss a stranger) or outright gender preference.

Sims who are already OK with make out, kiss, etc... are proven to be at least OK with the other party's gender, but maybe Woohoo option is still a bit too much for them.

If we are to discuss about this weird problem of refusing to woohoo, then it may have something to do with default value settings. There may be a mod, or a glitch, that altered the relationship value needed to conduct a "woohoo" interaction. For example, and for example only, friendly hug requires 10 points in relationship, hold hands requires 20, Kiss require 50, and maybe woohoo requires 100 (these numbers are fabricated, don't disagree on them). But if there is a tunning mod accidentally slipped in to cause value needed to woohoo to be something at 300, then the sims would have a long way to go from Kiss and Make out before they can even consider Woohoo.

The problem is there is no flashing green light to tell you when it is OK to even consider asking for Woohoo (much like real life) so players' common sense is the only thing we can rely on. But if these numbers are off, we are as good as blind.
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However, Woohooer SHOULD really make woohoo painless. Too casual for my taste (or for anyone's taste really) that Woohooer must be configured non-autonomous. Taking casual sex to a whole new (and very creepy) level.

I think I did have Woohooer on autonomous once, one of my male sim who just moved into a new apartment met a couple NPC chatting outside, and within 2 minutes of me working on something else, this male sim conducted "homosexual interaction" within the elevator. This is one of my main sim and I already set his gender preference to be heavily into female because he is meant to be a womanizer in my world. YET, woohooer took his "innocence". If any of you think this is a turn-on, think again. Autonomous woohoo without relationship check can almost pitch any 2 sims together and let them get it on. It can be an elder and a teen. Can be someone's elder mother and .... just too nasty. Anyway, since I also have AwesomeMod whose creator is personally against Teen-Adult relationship, whenever this randomness of woohoo happens, my game Crashed to desktop!!

Maybe they were born that way.

"...the gender preference has been given an initial value upon creation of the household, without us users knowing" is another way to say "they were born that way" in TS3 term.

In fact: "they were born that way, without their gods (players) knowing!"