It turns out that there's a scientific reason why complementary colors look so good together: The cones in your eyes use a careful balancing act to ensure that you see color correctly, and when two opposite colors enter the eye, they stimulate both low-frequency cones and high-frequency cones at the same time.

Do complementary colors go together?

Complementary colors are pairs of colors which, when combined or mixed, cancel each other out (lose hue) by producing a grayscale color like white or black. When placed next to each other, they create the strongest contrast for those two colors. Complementary colors may also be called "opposite colors".

Why do complementary colors look bad together?

Any time you place two complimentary and relatively pure colors next to each other you create visual conflict. Since the two colors have similar color strengths and are polar opposites in every other way they compete with each other for visual attention and end up looking discordant.