I had a similar situation about 30 years ago. I was a freshman in college and had always been pretty sheltered. In fact, I lived at home and commuted because my parents were THAT overprotective. There was a cute guy in my late-afternoon Algebra class and once in a while we'd chat after class. One evening, after DST had ended, we talked a bit and he asked me to go to a movie with him the following week (he belonged to a fraternity and lived in the House, so he was more tuned in to activities on campus than I was). I was excited, and hated to end the conversation to go home, but knew my mother would be wondering why I was late.
When I excused myself to leave, he asked me where I had parked. Because I did not have a class until after 10 that day, I had been forced to park in one of the more desolate parking lots. Because it was becoming dark, he offered to walk me to my car, since it was a long way, and a female walking alone to a deserted lot after dark was vulnerable. All he asked was that I drive him to the dining hall on my way off campus.
I wasn't really worried about walking alone on campus, but if he wanted to walk with me, and we could spend a few more minutes together, I was happy. When we got to my car, things got really ugly really fast. I did not do anything to encourage him, no alcohol was involved, and there could have been no question in his mind that what he did amounted to rape. He literally tore the buttons off my blouse, pinned my head under the armrest, and when it was over, and he noticed I was bleeding, he said "Oh well, there had to be a 'first time'."
At the time, "date rape" didn't exist as a concept. I had agreed to go out with the guy, so it was clear I liked him and was attracted to him. He was a BMOC, so he could have probably had sex with a lot less drama, so I wasn't sure what to think. Furthermore, he did not get out of the car, as he still expected me to drive him to the dining hall (which I did). I couldn't let my parents find out (they would have blamed me) and although I did not tell anyone, or conduct a survey, I know most of his frat would have backed him up with an alibi, or by claiming they too had slept with me. While I had not planned have sex with him that day or anytime soon, there was a possibility that, had we dated a while, we MIGHT have evolved into an intimate relationship. How could I argue that he had raped me?
The day we had planned to see the movie, we had a test in class. I finished quickly, and sat in the hall to wait for him. 30 minutes later, he came out of the room, with his arm around a girl I knew from rushing sororities, and walked by like I didn't exist. The NEXT time the class met, I noticed that she appeared to be about 7 months pregnant, though she wore clothes that disguised her condition.
At that point I was mad, but did not "decide" it was rape ONLY after finding out I had been "used." I found out I had been used a week AFTER I was raped. Things have changed a lot. I'd never hesitate to report him if it happened today, but at the time, I was concerned I would not be believed, and may even have doubted that it was REALLY rape, since it was a guy I "liked".