The main reason slut-shaming occurs is because of jealousy by other women, and because wider society is subconsciously aware that women are more biologically primed towards demisexuality than sluttiness (aka pure allosexuality).
Both men and women have negative views towards promiscuity.
Promiscuous women themselves view female promiscuity negatively. This is a form of bias blind spot in which people are unaware of how their own actions are perceived by others. This is similar to how tattooed people negatively judge other people with tattoos.
Many religious condemn promiscuity as a sin.
Secular slut-shaming is slut-shaming justified not by religion but by logic. This form slut-shaming is intended to curtail the negative consequences of female promiscuity such as hypergamy.
See also Sexual revolution - Section “Effects”.
Familial slut-shaming refers to the protective behaviors by fathers to their daughter's sexuality, and brothers to their sister's sexuality.
Fathers often get protective of their daughters. Fathers will often not allow their daughters go to parties because they are afraid of their daughter getting fucked by some alpha male. There is a possible evolutionary explanation for this. If the daughter got pregnant with an alpha male, but the alpha deserts the daughter right after, her child would lack paternal investment. This would force the father to expend increased resources to support his fatherless grandchild. To minimize the risks of having a fatherless grandchild, the father must expend energy to fend off males, particularly masculine males, who seem to have low commitment abilities.
Men should prefer the feminized version to accompany their girlfriend on weekend trip to another city. Both men and women should prefer the feminized version as a son-in-law because “he” would be less likely to desert their daughter and reduce inclusive fitness though the aversive effects of father absence (e.g., Draper & Harpending, 1982, 1988) and possible diversion of resources that could be otherwise allocated to additional kin. Women should also predict that their parents would prefer them to date the feminized version, as “fatherless” grandchildren may consume the resources of maternal grandparents, which could have been expended on other offspring to enhance inclusive fitness.
Mothers get protective of their daughters too, for the same reason. Brothers get protective of their sisters, again, for the same reason.