You see, if you note CC's post you will see, if you are not the one and only then you are never too far away from another mans juice, be it one mans, or more than one is not important. And to be honest, do long termers in DR really find screwing around aimlessly all that interesting or even enjoyable, or even having a bit on the side knowing it goes nowhere (which I guess is your question). I know we are not all the same, but surely once a guy gets to a certain maturity and has had sufficient experience (especially with Dominican women who are boring as hell unless there is also something between the ears) with women, his appetite levels out and requires slightly more than the guarantee of sex, which is the easiest thing in the world, second only to breathing in DR.
I guess my answer is in DR, being man #2 is pointless, besides what is mentioned above, nothing is more dangerous in DR, probably responsible for the majority of domestic deaths/murders.
Even on an expat level, DR attracts the craziest people around, even expats are another level of nuts, of all places in the world I would not feel at all compelled to go with another guys gal (expat or native) it is in DR.