Pluto (transformation, also power) conjunct Venus (relationships) can indicate someone who is powerful in or over-powered by relationships. If his chart time is close to correct, most of the planets in his chart are on the top left of his chart, indicating he does things for himself in the outer world, while most of your planets are focused in the top right of your chart, indicating you do things for others in the outer world. This suggests that he may feel powerful in this relationship, as the things you do in the outer world most likely benefit him as well. Saturn in relationship charts can add structure to the relationship, particularly when it is conjunct Venus. The close conection of his Pluto to your Saturn suggests a power-sharing of some type: him supplying the power and you supplying the structure for the mutual benefit of the relationship. Libra (relationships) modifying Saturn (duty, also structure) focused in the 7th house (relationships) intensifies the energy of the structure you provide to the relationship.