I guess it depends on your definition of "rational". From a pure logic perspective (i.e. the math definition) being rational just means making optimal choices in pursuit of your goals. I can be perfectly rational, understand that others have feelings, and simply not care about them unless they benefit me. Being perfectly rational basically makes you a sociopath, only considering other factors or people when they further your goals. Emotions and feelings are irrational to begin with, but sometimes it's better to be a little bit irrational