Here are a bunch of studies I posted in the last thread that show why. You kinda ignored these.

This guy puts the data together across multiple studies far better than I could. Combined sample sizes in the tens of thousands;

1 , 2, 3, 4

No, I won't tl;dr. This stuff is interesting.

If you really need one though, http://freenortherner.com/2013/06/21/sexonomics-odds-of-divorce/ does a very provocative summary of this(http://www.cdc.gov/nchs/data/nhsr/nhsr049.pdf).

Other links if you like sifting through data on your own(distinct from above): http://www.ncfr.com/pdf/press_releases/PRESS%20RELEAS2.pdf http://www.hookingupsmart.com/2013/11/25/hookinguprealities/casual-sex-bums-out-both-genders/
http://s3.amazonaws.com/thf_media/2003/pdf/Bookofcharts.pdf

tl;dr the risk increase from a promiscuous woman competes with the risk increase from uneducated woman really well. It outcompetes it at just about 2-3 partners. A woman with around 6-10 or more partners wins the race by miles.

EDIT: Someone gave me some interesting summarized graphs to include for those who are lazy. It's not just divorce. Its infidelity. STDs, depression, unhappiness.: https://i.imgur.com/rrLe319.jpg

http://nationalmarriageproject.org/wp-content/uploads/2014/08/NMP-BeforeIDoReport-Final.pdf

http://www.jstor.org/discover/10.2307/352992?uid=2&uid=4&sid=21104723503417

http://www.ncbi.nlm.nih.gov/pubmed/16131411

The results of moderated multiple regression analyses revealed that a respondent's number of sexual partners, level of dysfunctional impulsivity, satisfaction with current relationship, and quality of relationship alternatives significantly predicted inclination to engage in both of the extradyadic activities

According to the multiple regression analyses, number of sexual partners is a significant predictor.

The reason TRP disparages sluts is because the rest of the BP world tries to convince you, you should like them. For no real reason. TRP takes up the mantle and says no. There are a lot of reasons why they're objectively likely to be poor choices.

Besides being a great risk for not only divorce, but relationship dissatisfaction, promiscuous women are also unappealing emotionally to a lot of these men. Call the reasons whatever you like. But a guy doesn't feel an emotional and probably sexual aversion reaction to a marriage with a poorly educated woman. He does to sluts.

For some guys, innocence and femininity even turns them on. shock-horror. A college degree does not.

And lastly, you are operating under the assumption that RP really cares about these divorce risks. Not just from promiscuity, but for any risk factor. It really doesn't. They're just data that supports a choice we would've made anyway.