In my mind, sex is a caring act completed between two people who are comfortable with each other. It involves an understanding about what each other likes and dislikes, and a constant awareness of each other, so that if one partner starts to feel uncomfortable the other picks up on that and checks what the matter is, and stops if needs be.
The impression given by media discussions about rape is that sex is something a woman either agrees to or doesn't agree to. The issue of consent is contentious because it is not the experience of most people who have had normal sexual contact that there is agreement or disagreement, it is just a constant process where through body language, eye contact, verbalisations (not necessarily words), physical response and laughter you and your partner send each other signals that everything is ok or not ok. A person who genuinely wants to engage in sex will want to do so only if their partner is responding positively, as for a non-rapist that is the main reward and turn-on in sex. Without that response, most normal people would feel deflated (literally or figuratively!) and not be able to continue. It's not a matter of "yes" or "no," it's a matter of ongoing mutual respect where each partner is highly aware of the others' state of mind at all times. In a caring situation such as this, the likelihood that you will go ahead and do something that your partner really doesn't want or like is very low - you will see straight away that they are not happy and you will stop.
Rape is not sex. It is not a caring act. Just as stealing is not a form of borrowing, rape is not a form of sex. It is a denial of the other person's right to have control over their own body, and any level of that denial - whether it be holding the person down, or not stopping half way through sex because they were enthusiastic to begin with - turns the act from sex into rape. Once the sense of awareness of the partner is gone, sex ceases to happen.