It's not uncommon for women who are sexually assaulted to not report the crime right away for a myriad of reasons -- shame, lack of faith in law enforcement, unwillingness to relive the trauma in court -- and sometimes they even engage with their assaulter after the fact, again, for many complex reasons that don't excuse the crime. Trauma can make people do things that we can't always understand.
And all these reasons are irrational. It may be common, but that doesn't make it right. Train your daughters to have agency and look out for themselves, and these reasons all disappear.
You need a clear "NO" or clear "STOP" before trouble starts; if you don't want to have sex, say so clearly. Once you have said so, the situation is clear. If you have done so, and they stop, great. That is what should happen.
However, if the other person keeps going like what you just said doesn't matter, then they are forcing you, they are raping you. Escape, make noise, fight like hell, and report it as soon as you're physically able to. When you report it, tell the entire truth, holding nothing back. At least that way, you'll know within yourself you did the right thing, even if it goes nowhere after that - even if the cops are mostly a bunch of sneering assholes, even if the perpetrator is some sort of big shot, even if your "friends" are more likely to turn against you, even if your case gathers dust for 20 years. At least there will be some record from right away of what was done to you. It also helps you survive the trauma - if the guy knew clearly you did not want what he did to you, then it is
all on him for having done it, not you for having failed to stop it.
Every girl growing up should be taught this. Maybe it is not much more than an ideal, but the importance of that message should be clearly sent, not downplayed in favour of some false narrative which tells them that all their behavioral idiosyncrasies will later on be overlooked, in either a court of law or the court of public option. It won't be. It can't be, because such a position is indistinguishable from someone who had consensual hook-up but comes to regret it and years later decides to villainize the guy rather than own up to having fucked the guy willingly.
Saying the other person used coercion, force, or threat of force / retaliation, when they did not, is just straight-up dishonesty, even if one of the people you now lie to is yourself. There's no excuse for it. And every false complaint of rape undermines every true one.
That's why the law has to work a certain way, why it must be skeptical and seek facts in some cold-blooded way. It fails when it gets caught up in dogma or drama, and believes either everything or nothing, then judges based on assumptions. As always the problem with the legal system (and life generally) is how do we tell the difference between honest people and liars? If that's all there ever was, legal proceedings would just be popularity contests (and accomplished liars always win those). No, what is needed for justice - always - is evidence. Evidence is not just physical, it is also the record of one's conduct which points to credibility. Teach your kids that too. The world is unjust and dishonest, but you shouldn't be.
Once again, we arrive back at: "NO" means no, "STOP" means stop, "unconscious" means leave her the fuck alone because she can't consent - but saying nothing can only be interpreted as nothing. Ambiguity does harm, and can't ever provide justice. Clarity and honesty are the only true path to it.