This is in response to the discussions that Trinity started at her place and at Let Them Eat Pro-Feminist Safe Spaces about what women's libidos are actually like.
Not to generalise from a small sample (but everyone does that!), I want to ramble about things that I note have an effect on my libido and have seen other people dealing with. Just anecdotal data, of course, but maundering in directions that I find reasonably illuminating.
Relationship age shifts
My experience of my sexuality with a partner is that I tend to be very intensely sexual for the first six months or so of the relationship (more if there are distance issues); I also experience emotional spikes that often translate sexually when seeing someone after a long time apart. However, this intensity does not last; at about a year or a year and a half into the relationship, it has drifted down to a significantly lower and stable level.
Definitional issues
A lot of people seem to equate "libido" with "how often one wants to initiate or seek out sex". The thing is, for me, that's almost never (outside of the early phases of a relationship); it's not something that I tend to seek out. The thing is, my libido almost entirely runs on responsiveness to stimuli. (Early in relationships, I think the major stimulus it's running on is 'Partner nearby! Woo!') If I get the right things to respond to, I can respond very strongly -- and some of those things are difficult to articulate or isolate as stimuli.
I see people talking about masturbation frequency or use of porn as something keyed into libido, and that tends to leave me baffled. My sexuality is intensely partner-focused, and by 'partner-focused' I mean 'specific people', which means that neither of those things satisfy the focus of my sexuality. Masturbation can take the edge off a "the partner I want is not available to me at the moment", but aside from that has no particular appeal. Porn is, well, to paraphrase a guy on usenet, "Sex happening to someone else. Why should I care?" It doesn't involve me or my partners, and I am moderately squicked by voyeurism, so I just don't get it. Relating either of these to my libido just feels like trying to relate golfing to my libido -- has nothing to do with the subject.
So what does "having a libido mean"? I tend to parse it in terms of sexual reactivity and responsiveness, because that's the way my sexuality functions. Other people seem to refer to it in terms of sexual initiation, aggression, or loose sexual energy. Are we even talking about the same stuff?
Depression issues
My experience with depression is that my libido is the canary in the coal mine; if my emotional system is going down, one of the first things that goes is my responsiveness to sexuality. Often, the way the sailing that part of the neurochemical sea goes, it's not something I miss or even note as absent unless it is brought to my attention in some way; I have had several multi-year periods of asexuality.
I recognise this as something that does damage to certain parts of my relationships; this does not help the mood problem.
Damage issues
I've written extensively about my experiences with sexual harassment and assault, even just in this space.
I haven't written about what effects that has had on my sexuality as much.
My first period of asexuality occupied most of the dissociative period after the assault, and it was clearly self-protective. It may also be a chunk of the origin of the depression/asexuality link; after all, if the correct thing to do to be safe at one point was to cease being a sexual entity, then that's a pattern that worked once. Why not try it again when under similar stresses (isolation, anxiety, trauma)? I honestly have no clear sense of continuous memory with the person on the other side of that; I can pull up facts, but they're not entirely contiguous with my sense of self.
At my best guess, the person who would grown out of a version of me who was not assaulted would have been a good bit more sexually open. Probably would not have been one for casual sex, but might have been more comfortable and fluid with friends-with-benefits sorts of relationships. Would have had a clearer sense of sexual exploration rather than sexual danger; would probably have been less reckless in initiating sexual relationships. Might not have as strong a distinction between physical and emotional arousal. She might have masturbated occasionally, or might have come to the conclusion, after some more experimentation, that the sensation was not satisfying.
Physical arousal and mental arousal are only loosely linked for me. Most often, this manifests as physical responsiveness (getting wet, etc.) without associated mental/emotional "I'm turned on/horny/interested in sex", though it has occasionally manifested the other way around. This has meant, among other things, that the studies that show physical responses and purport that to have to do with arousal have always left me cold; my sense of arousal is much more mental than physical, and I can have one without the other. I wonder how much of this is because of having a history of dissociation around sex, and how much of this is that physical arousal is somewhat less overt for me than for a man -- lubrication doesn't always register to me as something to be aware of, so I don't have to work out questions like, "If I have a physical response to this, does it mean sex is warranted?" I know of people who assume that "erection" = "sexual arousal", despite the fact that the physical response is fickle and responds to a variety of things; I wonder, also, whether that confuses things any.
I used to get flashbacks. (They are, at this point, very rare, and mostly controllable.) The trigger for those flashbacks was the sight of an aroused and erect naked man, especially of a particular body type. As flashback triggers go, this one is rather inconvenient if one is a heterosexual woman. Wrestling with the flashbacks, especially at times when I was just not feeling emotionally strong enough to explain what was wrong or even mention that something was wrong, is utterly exhausting in demoralising ways.
For a variety of reasons, I get easily messed up by a sense of sexual pressure, with any sort of expectation that I should be more sexual or more readily sexual than I am. Some of this is self-inflicted trauma from personal esteem issues interacting poorly with other things -- I, basically, wind up with tremendous complexes about my value as a partner if I'm not sexually available, which, once they exist, wind up setting off depression issues very easily, and, of course, make me unable to sexually respond smoothly or without extensive effort, because I need to have the complexes soothed as well as the responses evoked. This is a self-perpetuating bloody mess, as I get into a mental state where any sexual approach that doesn't synch up within a very narrow band of response triggers completely tenses me up. And I don't know how to fix this, which depresses me, which ....
Kink compatibilities
I've learned from experimentation that I cannot sustain a relationship well that doesn't have a certain level of kink compatibility. What I actually need is the ability to have my own kinks be expressable and not remarkable when they tend to show up; on the flip side of that, I can't handle dealing with too much stuff that just doesn't turn me on in my sex life.
A bunch of my kink stuff is very strong sexual responsiveness trigger, too; a good mesh can lead to a bunch of things raising energy very easily. This doesn't mean I don't have responsiveness to non-kinked stuff, but it does mean that the more I can synergise with someone on this front, the easier it is to be sexual.
Cultural stuff
There's a whole hell of a lot of weird pressure out there on sexuality. Not just in the whole cultural assumption that women must regulate male lust in some way rather than having desires of their own, or the notion that even if one does have sexual desires one should not express them for fear of being inappropriate, too forward, too pushy.
A friend of mine in high school completely flipped out when she learned I was sexually active. Completely, totally lost it. Because she had seriously bought into the whole Sex Is Dangerous propaganda of the upswing of the AIDS panic -- someone who was sexually active was going to come down with a horrible disease or die. Or become pregnant and ruin their lives. Or something like that. Crazed panic. The whole mythology that it's impossible to be responsible about sex was one of those things I had to think about a lot, especially given my reckless tendencies as a result of the trauma.
There's no teaching about how to think and communicate about desires, which makes it harder to articulate and present them. Which makes it harder, at least for me, to be able to express what I want, talk about the hidden desires, and so on.
And the difficulty of talking about things ramps up harder and more vicious around kink stuff. The stuff that I fantasised about when I was telling myself stories to go to sleep by is all stuff that a lot of people tell me I Shouldn't Get Off On, and that makes it harder to go there, harder to admit to it, all the complex tangles of the need to, basically, come out to oneself.
(I managed to avoid the "good girls aren't sexual" stuff, but I know people who didn't. I also know people who caught a bad case of "Only assholes have and express sexual desires".)
Inhibition and Expression
I am far more interested, sexually, in a communicative lover than an unexpressive one. Sounds, facial shifts, physical response, it's all good; if I don't get something like that, my own responses tend not to kick in, or not terribly strongly. It is far easier for me to express myself sexually with someone who is sexually expressive and does not manifest hangups and glitches about sex (whether culturally induced, history induced, or whatever else); I have enough sexual glitches for two.
So that's a few things that I know play into how my libido responds. I used to have a joke that I had the libido of a philodendron -- I bloom profusely once a year -- though that's less accurate these days. It's still not a bad joke, in a lot of ways, because the entire process is fraught and complicated and sensitive, and I can't help but wonder how much of the play of all of these factors might be a part of the whole mythology of women wanting less sex.
Some stuff to think on.