Our green cones are the most sensitive and their range significantly overlaps with red cones, so it's only natural that going from green towards red you'll be able to make clearer distinctions between colors than the other way.

Also, yellow-blue and red-green are opponents that can't be mixed because of how our retinas preprocess the signals from cones. Therefore, you obviously end up with blue-green (cyan), red-yellow (orange), yellow-green (lime) and blue-red (magenta, which actually doesn't exist on the light spectrum) families of related colors.