Reminder: First, let’s take out the weak/bullshit reasons about why it devalues women.
Her being unable to “pair-bond” after “x” number of partners. I don’t really buy into this, hard to prove, and hasn’t been my experience.
Her vagina getting stretched out. Nonsense. They are elastic. My experience has not shown sluts to be any looser or tighter.
Men are afraid of being compared to past lovers. This, of course, is women’s favorite assumption. While some young men may feel this way, most men outgrow it or are confident enough in themselves sexually not to give a shit.
Let’s get to the real reason: Female promiscuity is associated with low value traits. Her inability to gain commitment from the men she slept with in her past sends a red flag to the rest of us that she is probably not someone worth keeping around. Just how women take their cues from other women on which men to find attractive, men take cues from other men as well when it comes to assessing a woman's value. If some bum down the block pumped and dumped her, she’s probably not worth much more to you.
Once a woman sleeps with a man, the power shifts, and it’s time for a woman to show her value to him in order for him to want to keep her. He’s proven his value already, because if he hadn’t, she wouldn't be fucking with him in the first place. .
High quality women are able to get commitment. Men lock them down by marrying them and/or committing to them because they value what she brings to their life. These women have a very low turnover rate because men keep them in LTR’s. As a result, her number of sexual partners is low.
Women who have consistently failed to gain commitment from men they sleep with will be assessed as lower value, and their turnover rate and number of sexual partners will be much higher. Few men want to keep them around, and usually for good reason. These women display unattractive traits like clinginess, insecurity, low intelligence, laziness, unladylike behavior, etc. They are seen as unworthy of commitment and subsequently used for sex until they are bored or pushed to commit and dump them.
So we can conclude that a high number of partners for a woman is associated with low value traits. One only needs to look at the revolving door of men in an overweight or homely woman’s life to see this pattern.
Now, to illustrate the point about association of low value: Take a man who goes on dozens of job interviews, but can’t seem to get hired anywhere. People will eventually start to assume he is the problem. Exactly how many failed interviews he has to go on before people will start to think that is subjective, but eventually they will assume it is because he is lazy and un-hirable.
Men make this same subjective judgment based on a woman’s sexual past. Everytime she slept with a man who didn’t end up committing, that was a failed interview. That is why there is no set number determining when she’s crossed the line into unhirable status. For every man, this number will be different.
So, if female promiscuity is associated with low value women, why doesn’t it devalue men?
Because the man is the employer in the analogy. Women assume a man who has rejected a high number of sexual partners (applicants), but hasn’t found anyone good enough to commit to, that he must be a high value mate, and to be hired by him will put her in a good position.
A high # of sexual partners for a man is associated with high value traits. Women know this, which is why they don’t care how many partners a man has had. Athletes, celebrities, wealthy men, etc. constantly have women fighting for their attention no matter how many women they have had in their life. Promiscuity between the sexes is simply not comparable because they have opposite perceptive value.
Tl;dr Men are the gatekeepers to commitment, making our promiscuity irrelevant. Women are the gatekeepers to sex, making their promiscuity an insightful tool in assessing their value.