All trolling aside, Niara's right in real life. If either party doesn't want sex to happen, it's teh rapezorz. It's not like after being raped for the first ten minutes or so, they'll suddenly decide the sex is so good that it's making them horny.
But you knew that. Because you're all clever people and you have access to Google and common sense.
It is a sad fact of human nature that what the OP describes as "reluctant" is hella arousing for some people to watch. So much so that it was a key element of early porno and remains a potent meme to this day. Just like nobody in porn has to worry about STDs, the orgasm has to involve a cumshot or it didn't happen, and all pool cleaners have the iron body of Hercules.
I think most of the people on this forum- certainly the programmer types- are smart enough and mature enough to recognize this for what it is. It's a conceit of the artform. It's a trope. A lazy writer's visual shorthand for the concept of seduction. And our monkey brains are hard-wired to accept it, as long as it's presented in an appealing way.
That's fine. As long as you're watching fictional porn.
If you use it as a guideline in your love life, I'm sorry, you've been hurting people.