I've been with my girlfriend for nearly six months now. I've always had a bit of a problem having sex with people (keeping it up) but this problem has never occurred between me and her. However, lately I've begun to feel very guilty about the physical action of having sex. The act of penetration is a great experience physically, but when I think about what I'm doing I feel like I'm stabbing her, or performing some kind of violent act on her. We haven't had sex yet since I started REALLY feeling like this (which was a little more than three weeks ago) but if we are making out and begin to have dry sex I often start to cry from the idea of what I am doing to her. She's very compassionate and understanding, and I have told her all of this, but I want it to stop. I need to know how to make myself stop feeling like I am abusing her when we have sex because considering the times we've had sex before I had this mindset, it's been an incredible experience of expressing our love to each other, and I'd really like to have that back.

What is the difference between oral sex, manual sex, and anal sex?