Mars shows what a woman is attracted to in a man. Being with a man who is strong in her Mars element, or who makes close sextiles with her Mars, makes the relationship much easier, and increases sexual desire and compatibility. For a man, his Mars is part of his masculine nature, so it is best when his partner also relates well with this element.
Mars Square Sun
A Mars square Sun aspect emphasizes the challenge of assertiveness. Each partner brings enough ego into this relationship to cause an unhealthy amount of competition between you over who directs what. You can meet this challenge favorably if you can agree to place this energy toward a common goal. When the Mars person is square the Sun person you can feel challenged by your partners need for dominance.