Step 1 to handling the concept of rape: If your partner says you didn't have their consent, you should assume you didn't. Even if you really thought you did at the time. Even if you really really thought everything was cool.
Step 2: There is no step 2. If you actually follow step 1, all further actions will be sensible.
No... If someone gives consent, they can't later retroactively make you a rapist by retracting it. That's not rape, that's probably regret.
A healthy relationship does mean setting and respecting boundaries, though.
Giving benefit of the doubt to all parties means*, "Well, she says she was raped, so I'm going to take her at her word", and "Well, he says he wasn't trying to rape her, so I'm going to take him at his word", and going from there, noting carefully that those are not mutually exclusive statements.
You're suggesting that, in that case, we simply take her word that he raped her. And that he didn't mean to rape her, but did. Dogmatic belief in false victims greatly weakens faith in actual victims. If we're told to trust all accusations implicitly, we end up trusting none. "Oh, just another lady 'raped' because she was embarassed". That's horrible, because (and I hate to have to keep repeating this): Rape is one of the worst things that can happen to someone. It is NOT waking up with a hangover next to an ugly person. It is about being forcibly violated, against your will. Being drugged is not the same as drugging yourself.
It doesn't mean that you need to take time off from talking about the actual actions that occurred to debate the fucking semantics of what does or does not constitute rape, nor does it mean that telling people "You weren't really raped" is preferable to diluting the word.
The "fucking semantics" are important when people go to a bar, drink, go home with someone, have sex, then claim they were raped.
Because here are people claiming that that's rape, when the other partner has done literally nothing to force sex on the first partner.
People are innocent until proven guilty... Legally. Media and community are not so just. Being labelled a rapist can ruin an innocent person, especially if they start to believe it.
*You can swap the genders of the pronouns, it makes no difference and was an arbitrary choice.
What, did you flip a coin? If it was actually arbitrary, you could use gender-neutral language instead of framing it in the stereotypical male-vilifying way.