Consent is too often treated as this magical concept that makes everything right when it's present in some form. Many people seem to think of consent as a "yes" when often it's more a lack of "no". Someone not protesting or going along with something doesn't absolve the other party of responsibility. Heck, even explicit consent doesn't do that. Would you accept someone repeatedly offering another person in their company drugs when that person hasn't outright refused them but not really shown interest either?
When someone goes along with something but ends up feeling uncomfortable or even resentful about it, they can talk about it with the other party. And that party should acknowledge it. They may have meant no harm or even be surprised or feel hurt, but a decent person would consider the other's feelings and admit they may have had poor judgement. This Jon Pretty guy allegedly has a pattern of maneuvering women into vulnerable positions, inappropriately bragging about his "conquests" and from what multiple sources confirm shows a bunch of telltale signs of an emotional abuser and manipulator. It wasn't one instance of them being drunk, it was an extensive period of pushing boundaries, coercion and probably gaslighting.
You'll always hear questions along these lines. "Why did she stay around him if she was uncomfortable/mistreated/abused?" "Why did she wait so long to talk about it if it bothered her so much?" "Why didn't she collect proof?" "Why didn't she just say no?"
These questions interpret the situation as far too simple. Abusers are great at creating doubt. They do something wrong, they make their victims feel as equal accomplices. Good and fun times are alternated with bad ones. They don't outright break the law or force someone but will push boundaries and wear someone down repeatedly to get their way despite the discomfort of the other.
That's why it's so hard for a victim to come forward. It's exactly because everyone says "well you didn't set hard boundaries, did you?" It's because maybe no crime was committed according to the letter of the law so they don't feel like they really have a case to make. It's because the victim initially feels like they share as much responsibility or it's their own fault and they should have known better. Abusers are great at walking that line where they get what they want while still maintaining plausible deniability, making it impossible to fully dismiss the argument that the other person is responsible too. It lets them justify their actions to themselves and others, believing it was as much the agency of the other party as their own. Meanwhile they're constantly using a position of power and a victim's weaknesses to manufacture precisely the situation they want.
They call them predators for a reason. It's cause they seek out prey. They know what to look for in a potential target. Don't blame a victim for being possibly naive, inexperienced or easy to sway when those were exactly the preconditions to be taken advantage of. It doesn't justify someone doing just that.