Loyalty and Honesty are two virtues with a lot of in common, but both RD and AJ are too dominant and competitive to make a good couple. They can be the best friends around, but as a couple, they would been always arguing.
RD needs somepony who softens her strong, stubborn and proud personality with patience, empathy and kindness. In other words: Fluttershy xD
And Fluttershy needs somepony who knows her inner strenght and helps her to be stronger and more confident. In other words: RD xD