In the not so recent past, and even today men had most of the power and money in relationships in the Dominican Republic. If you have never lived in poverty you have little understanding not to have to scrabble for food and shelter. This was the situation for most women in the DR so they put up with their husband or father of their children having other women. Culturally as catholics it was more than just frowned upon, but also divorce was almost impossible. Many of those conditions still exist for the uneducated poor women in the DR. So yes it is in the culture but not really accepted. I work with 40 plus Dominican women, some married and some single. Most of them would cut the balls off their guy if he was screwing around on them, and they certainly would end the relationship. Lots of divorces in the DR for this very reason.
"Cut the balls off their guy"? Not fond of how that comes out. I know you are speaking metaphorically (for the most part) but if I said that a guy would "Cut the tits off of his woman" if she were having sex with other guys or acting coqueta -which is exactly how over 70% of Dominican women act when around a guy they are into, or just to go walking around the street wearing tight or revealing clothing -all of sudden we would need to have a "Domestic Violence" conversation that drags men through the mud.
NO one should be cutting anything off of anyone.
Back to the topic at hand - I've spoken amorously with over a thousand Dominican women. I agree with you that most do not see it as "ideal" that their guy be with other women. That said, the culture here specifically allows a man to be with multiple women "if he does it right", is the phrase that is commonly used. This includes not being seen in public places, not bringing home children or diseases, and not neglecting his responsibilities to the home, primarily the financial ones. When a man is 5'11 or 6'3 or 6'6 and he has a square jaw and he is fit or in shape, he is getting around, period. Even more so if he dresses professionally and/or has a job that brings in serious money. And the women that he is with know this, and they tolerate/accept it because they value being with him more than they do being the only one that is with him.
That said, I will agree with you that there are lots of guys who don't fit this caliber and are mujeriego and their women do (eventually) get fed up and leave them. I will also agree that in general it is a difficult thing for a Dominican woman to accept. That said, culturally it is widespread, common even, and not a secret. It happens, every day, amongst every social/economic class.
I don't want to keep having to rehash this conversation but I know it'll come up over and over again. Dominicans aren't living in the kind of "poverty" that requires them to "scrabble for food and shelter." And it's a really disingenuous statement to make. MAYBE 20-50 years ago, I don't know - I wasn't here and haven't done enough reading to say otherwise. MAYBE some of the Haitian population could be described as being in that situation currently. But how many indigent Dominicans do you know living in the forests and jungles of this country without a roof or on the streets sleeping on cardboard? Eating once every 2-3 days? And then how many 18-25 year old girls do you know with Iphone 12s and 13s? 30-40 year old women going back and forth to western union collecting more money monthly than you do with your job at the school? Guys who are connected receiving remittances (through women that they set up as mules) from different black and gray market channels? Maybe people are confusing the Dominican Republic with Cuba, or maybe you are just comparing this Island and it's people, which has it's pros and cons to the most economically powerful nations on earth - the USA, Canada and those in Europe? Apples to oranges. All you need to do is walk inside a PriceSmart or Jumbo and see Dominicans every day all day walking out with big screen TVs and stereo systems and carts full of items to dispell this ridiculous myth. This country ain't in poverty, not by a long shot. Also, a lot of the conditions that a 1st worlder would consider as immediate "Poverty status" aren't seen the same way here. A zinc roof, no electric, or electric borrowed from neighbors, living a ways from the nearest city, living on streets that are absolutely filthy and/or where there is lots of barrio noise, living amongst individuals or being an individual that doesn't have a formal education, etc. etc. These are not indicators of poverty, as much as they are conflating contemporary "Western" standards of living to other countries. The DR is in a rapid period of growth/development and it's normal to have infrastructural challenges when a country is rapidly developing. Think the late 1800s, early 1900s in the USA.
The people are well fed (overly so) with extremely fresh and non processed food (and processed foods are of course available as well), mostly everyone has a home or two or three they can be in, though it may be living with an aunt or uncle or a brother or sister, and for those who want it a job is not a difficult thing to find.
Bob - when I took the Ruta Panoramica from PoP to Santo Domingo I saw 3-4 of those "party busses" - old yellow schoolbusses fitted with lights and speakers, full of (lower class) Dominicans getting drunk and grooving out doing turismo interno. You ever seen them? Does that seem congruent with a country in which there are a significant number of people "Scrabbling for food and shelter"?