I think men are generally the same, regardless of nationality. We like to think we are the first, only, and last.
That having been said however, most of us know we're not the first, so we let that slide. We also suspect we won't be the last either, once the relatiohship is over, so that is forgiven.
The big one is the "only" part. That is, "only" being defined as exclusive sex during the course of the relationship. There is no way around that one.
Part of that need for exclusivity is biological, with men wanting to protect the origin of their genetic lineage. Part of it is the natural competition between men, and that involves ego. But I think, for me at any rate, a large part has to do with the issue of trust.
A man wants to trust his partner, to know that the confidences he shared with her will not be shared with others. I don't know if that is a universal trait, but I do know it is true of many American men. We do not want our weaker moments to be exposed to our competition, and where love is concerned, the competition is all other men.
Now to bring this back to the OP's original query, in my opinion, while all men might get jealous, not all men handle it in the same way. That is where some of the cultural differences probably come into play.
Dominican men probably are more expressive about their jealousy, and might be somewhat more sensitive about competition. Where many American men simply move on after discovering an infidelity or breach of trust, the same might not be true of Dominicanos, who seem to care more about their peers think of them.
All of this is really just conjecture, since I am not aware of any sociological studies on thnis subject, but it is conjecture based on my observations and experience. Anyway, it makes for an interesting debate, and love is one of the two things that make the world go 'round.