In relationships where there is a strong compulsion to be with each other or where one person feels compelled to be with the other there commonly is a strong Pluto (transformation, also control)/8th house-Venus/7th house (relationships) connection between the two people. In this case his Pluto conjuncts (energy is combined with) your Descendant (others - edge of the 7th house). This indicates he has control over the relationship. It is possible he COULD let go, but likes to be so completely in control. In these cases you might what to consider whether YOU like being so completely controlled by him.