I wrote this little thing out about a year or 2 ago regarding this just for myself. I have it saved in google docs. Overall, more research is needed, but yeah just looking at it from an epidemiological standpoint, even after accounting for other factors, sexual promiscuity is harmful to long term relationships,
especially when it's by women:
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Oxytocin (and vasopressin) are chemicals that are released during sexual intercourse (
1) that form pair-bonding and monogamous behaviors in mammals (
2). At baseline, females tend to have higher levels of oxytocin than males along with more oxytocin receptors (
3, section 1.4). We know that women who have impaired oxytocin/oxytocin receptors typically have trouble with social relations and are more likely to have marital problems as well (
4). In addition, inability to form social attachments is associated with a variety of psychological disorders, as noted in the DSM-5 (
5). Women have higher oxytocin levels during arousal and orgasm than men (
6, p. 74).
Just as an aside, females are more monogamous than males regardless of neonatal development/hormone exposure, and are less likely to form female-female bonds when they have elevated oxytocin levels due to jealousy (
7, section 6.5; section 7.3 states that feminization in physical attributes tend to show more monogamous behavior; section 5.2 states that more oxytocin AND vasopressin is needed in males to elicit a mate preference than in females).
That aside, it's also important to recognize this (
8, p. 95):
Working within genetic constraints, early exposure to hormones, including peptides and steroids, has the capacity to reprogram the developing nervous system. In addition, early experiences can alter the capacity of the nervous system to produce hormones, including oxytocin (Carter et al. 2003). Such changes can produce adaptive and, in some cases, long-lasting changes in physiology and behavior. Patterns of social behaviors seem to be especially sensitive to the effects of early experience (Pedersen and Boccia 2002; Carter 2003). It is likely that differences in the capacity to form social bonds reflect the social and endocrine history of the individual, the consequences of sexual differentiation, as well as species variations in neuroendocrinology and neuroanatomy
The above basically states how a person's first exposure to oxytocin is especially important. And knowing that oxytocin has an even greater impact on women than on men based on (
3), (
6), & (
7) means first experiences/exposures of it have a greater impact on women as well. When we look at this next study (
9), we find that oxytocin causes stronger emotional imprints, regardless of whether those emotions are positive or negative. Tying everything together so far, it means that the emotional impact of your first partner will typically be greater than any subsequent partners, and that this effect is especially pronounced in women more so than men.
But I mean, we already knew this anyway. All this did was just confirm and explain the stereotype about why virgin girls are clingy. And even if you disregard all of this, you can just use common sense: first experience = novelty effect = greater emotional imprint. And whoever that person is that you lose your virginity to, will forever be associated with that stronger emotional imprint. Not to mention, there are always greater experiences of love and infatuation in the beginning of relationships due to the novelty of said relationship, i.e. the honeymoon phase.
Now, why does all of this matter? Because repeated exposure to a certain stimulus and/or overstimulation causes desensitization (
10). This works through the same mechanism as drug tolerance: increased concentration of ligands cause a downregulation in receptors and/or the body's natural production of said ligand (
11,
12,
13). The ligands could be anything from your standard psychoactive drugs (
11) that affect neurotransmitters to exogenous hormones like anabolic steroids (
12), or even naturally-induced diseases such as type 2 diabetes (
13).
This isn't anything new, either. Studies show that when women engage in premarital sex, the chances of divorce skyrocket, whereas the same isn't true for men (
14). The only time it doesn't make a difference is when the person they have sex with is with the same person they will marry (
15), which basically means that they still only had one partner, who is now their spouse. Even more, this study (
16) shows how premarital sex and the factors that would make someone engage in premarital sex are one of the reasons that lead to divorce, after noting the very high correlation between non-virginity and divorce.
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There are also 3 separate pathways of reproductive motivation pathways: lust, romantic attraction, and male-female attachment (
17). This same study also says how when people fall in love, they are unable to feel romantic passion for more than one person at a time (p. 415) and references the novelty effect (p. 416). The researchers also noted (p. 417):
Romantic attraction is generally impermanent, unless physical or social barriers inhibit partners from seeing one another regularly.
And we CAN generalize some behaviors in mammals to humans because of this (
8, p. 95):
The basic hormones and neural mechanisms responsible for social behaviors are also conserved among mammals, and thus shared by humans and other mammals.
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So yeah, science.