Need help understanding this dream; somewhat disturbing.

[Riotfish]

This dream has been on my mind all day, and if anyone can help me out with it I'd be very grateful; I think I got a fair amount of detail in there, but if you need more I'll see what I can remember. The first thing I remember is that I had my girlfriend tied up. Not in a sexual fashion, but as if I were kidnapping her. She didn't protest (and in fact didn't say or really do anything until the end), nor did I really feel like the police or any authority was coming after me, but I knew that I had her bound against her will. I vaguely remember taking her to what, to me, resembled some kind of junk yard, but that part is only fleeting. The end of it is the only part I remember in detail, and it's probably the strangest. I took her to a hotel room of some sort (it was very small, the bed and a tv in a cabinet type thing were the only things in it), and put her on the bed. This is probably the worst part, but I think I was about to rape her. As I reached to take her clothes off, she looked up at me and smiled; in her face, it looked as if she didn't know where she was or what was going on, as if she'd been drugged or had gone insane or something. Then she said something very strange; I may not have it verbatim, but what I remember is, "I haven't gotten to spend time with [my name] in so long, Dad." The "Dad" part confused me the most because I felt in the dream that I was myself, and not her father. I should note that throughout the dream, I can't remember feeling any sort of emotion. Then, in my dream-mind, I "realized" that our relationship would never be able to be normal again after this, and my only option was to kill her. And then I woke up. Like I said, I was pretty disturbed by this and still am. Our relationship is happy, I just moved in with her and her parents, and we're going to the same college. For being as young as we are (19) we have it pretty good. It seems to me like dreams tend to blow things out of proportion sometimes, but this is just crazy. If anyone can give me some insight as to what the hell is going on in my head, I'd really appreciate it. As an afterthought, I've also had several dreams in which I was cheating on her, or I was with someone completely different (sometimes made up, sometimes not) and she had never existed.

[Inspirer]

You fell out of love with her and are only still with her out of convenience. You are ashamed of this and feel it's time to break up.