I assume "rams" refers to the varieties of the species Mikrogeophagus ramirezi, the common or blue ram. There are many varieties but they are all the same species. There is however another distinct species, M. altispinosus, the Bolivian Ram.
With both species, the fish must select their mate from a group. Any female paired with any male may or may not work, and one will be dead before long if they do not bond. You can sometimes discern a likely bonded pair from the group of fish in the store tank. Or you can acquire a group of your own, but then you will have fish to get rid of if a pair forms. Unless the tank is large, and sometimes even then, the male will establish his territory and allow the female he bonds with to remain, but likely not another. Especially if they spawn.