Well, if ruler of the 8th sits in the 7th that could indicate a very sensual, spiritual and maybe a bit mysterious partner or a person who gains/inherits money from the partner, because the 8th is also associated with shared resources and partner's money (as the 2nd from the 7th). All these if the planet is well aspected. If it is bad aspected, it could also indicate a partner with health, confidence or money problems.
But, on second thought, I would first look at the 7th house and its ruler and to a lesser extent at the 5th than at the 8th...