I think to a certain extent, that Hamlet is using Ophelia as a means to the revenge he promises his father. In addition, I think that he did at one time truly love Ophelia because not loving her is very undynamic, but I don't think that is that only motivating factor for him. Taking it one step further, perhaps he hates himself for using her, but at that point, can't help himself. He can't control the obsession of revenge, so it bubbles over into his behavior towards her. There is just so much going on!!!