The first part I would classify as regrettable sex. The second part? That's rape.
Does that happen? Yep. Absolutely. It doesn't even need to be 2 sex acts. I have been happily having amazing sex with someone, needed to stop, said so... And they stopped! Finis. Freeze. Pause. Done. Stopped. Right then & there. Oy. Poor guy. He was a really, really good one. I was just some random chick he picked up, didn't know me from Adam, no need or reason to be concerned for my feelings or anything else. Far as he knew? He'd never see me again. Except... He's not a rapist. In any way, shape, or form. The chick he was banging said stop, he stopped. End of story.
Been with other guys where one of us needed to stop for whatever reason, and yeah. Stop. Finis. Done. Right then and there. There is only one point whilst having sex where that's physically impossible, and it's only a few seconds long. Any time before or after orgasm, a person can stop. The cascading chemical thing that happens with blokes isn't something they have control over. Once the prostrate triggers, you've got 3-5 seconds of uncontrollable chemical reactions.
Regrettable sex... When it's bad for any reason, or even when it's amazing but you feel awful afterward for any reason, is still consensual.
Rape... Not consensual.
- Spousal rape? Happens. You can consent 5,000 times, then say no, and it's rape.
- Date rape? Happens. You can consent up to a point, and after that point (if they know), it's rape.
You consented for the first time. It was bad, and you called halt. But it could have been amazing. That part really doesn't matter. The part that matters is that you called halt. You did not consent, you were forced the next time. Which makes it rape.