Reading this, I think one thing I can take from this is that power differential is just hugely important to consider. Also, I can see how an aggressor might be able to rationalize this behavior in the face of no active protest and, as the abuse is allowed to continue, create a narrative of, "We had a tender, lovely connection." That is, in no way, intended as a "blame the victim." Undergrads are barely adults. The responsibility falls on the professor.
I could see in more strictly dating situations that consent and perception of become very blurry.
I am familiar with a case in which a high school band teacher, currently in prison for life, had sex with several underage girls (youngest being 14). One of the girls shot herself in the heart on his front lawn because of the relationship. Two others then accused him of sexual assault. It went to trial. He was found not guilty. But, it made national news. And, a few girls from a prior job in another state accused him right before the statute of limitations ran out. That got him. The details of these things were salacious. The girl that shot herself was portrayed as mentally ill (true). Another girl was portrayed as jealous (the fellow was also having an affair with her mother). There were racism accusations as well. Incredibly damaging.
The day after the girl shot herself, he stood in front of the classroom playing soprano sax and crying. Lectured on the transience of life. He also used to lecture on how boys should treat girls. He came off as an advocate for treating girls and women with respect. And, heavily portrayed himself as a kind of life mentor/guru. He took black high school boys under his wing and tried to instill higher self-worth, got them involved in leadership positions. He recognized talent and cultivated it. He saw when people were being mistreated or misused and righted it. He was charismatic, likable, talented, and gregarious. Our band won numerous awards with him leading it. The amount of betrayal in what he did for that group was palpable. I imagine he thought he was a good person. I imagine he didn't see what he did as wrong, that he must have rationalized it somehow.
I think that people that do these sorts of things are heterogeneous. Some are truly straight up violent and like raping women. Some are socially clueless and don't understand power differential, how to approach women, and how their behavior effects others (Louis CK, maybe? I haven't read too much in depth there. But, it seems like he might fall in that category). You look at toxic internet communities and relationships between men and women are discussed and you can see that there is an incredible gulf between healthy and unhealthy for many, many people.
In my opinion, we should be attacking this problem from multiple angles. I will teach my daughter to be assertive, to really drive home personal sovereignty; the goal being to try to protect her from the kind of predator you encountered. At the same time, we really need better decorum/civility in how people treat each other out in the world. Better emotional communication skills, and so on.
Operationally defining harassment/rape is important. In the news, we see cases in which due process is shredded (e.g., Duke Lacrosse, a case at Occidental college, mattress girl) that I think actually harm our ability to address these issues in a satisfactory manner.
There are so many tragic cases of this (what you experienced) out there in the world.