Mercury represents our communication style and intellectual processes. Strong aspects between your Mercury and your partner's planets and/or points favor communication and sharing ideas.
Mercury Opposition Sun
A Mercury opposition Sun aspect can be very difficult for marriage unless you can maintain a certain level of emotional detachment from the subjects you discuss. You will definitely see two sides to every story. Your intellectual relationship is what stimulates you, sharing thoughts, studying together, sparking one another's curiosity and interest is what your relationship is about. When the Mercury person is in opposition to the Sun person, you will be made aware of ideas you may never have thought about on your own and could find yourself defending your viewpoints in most of your conversations.