First, the legal definition of rape is much more complicated. Second, I think you would be hard pressed to find any police officer willing to arrest someone for "mutual date rape" when they get blackout drunk or an attorney who would prosecute. Third, your apparent belief that Marvel has done something wrong by "playing it for laughs" ignores the reality of what it is like to actually be in that situation versus the reality of what it is like to live in the aftermath of a sexual encounter where you have been taken advantage of or worse, forcibly coerced via any number of methods to do something against your will.
Essentially it is taking an overly literal view and forming some type of argument about the immorality of the situation. What do you think the consequences of this "mutual rape" should be? Should they be arrested? Does Peter need rape counseling now? If your answer to either of these questions is "yes" I think you should take ten minutes and reevaluate your understanding of the situation.