The Sun is the source of all energies. These energies stimulate the activities of the houses occupied by the transiting Sun and reinforce or weaken the planetary effects, depending on the Sun's aspect to the natal planet. When the Sun transits an inner planet, it may trigger a dormant aspect between that inner planet and a slower moving outer planet. If a planet is being transited by another planet when it is being transited by the Sun, the effect of the transit is strengthened.
Sun Opposition Jupiter
A Sun opposition Jupiter aspect indicates that you have a very different philosophy of life, living together and loving than does your romantic partner. You can go a long way with this aspect if you can develop a sense of sharing, by recognizing your partners viewpoints and each giving the other a turn rather than pulling in opposite directions. With the Sun person in opposition to the Jupiter person, you can feel that your luck is being stifled and your horizons limited by your partners relationship goals. Unless you develop communication and share your experiences you will lack the kind of love and understanding that can bind you closer together.