I’m really getting pretty damned sick of the infantile “enthusiastic consent” trope, which promotes a fairy-tale view of human sexuality in which the only possible reason for having sex is “fun”, the only acceptable form of consent is throwing oneself into sex with the wild and totally senseless abandon of a teenage wererabbit on coke, and all enjoyment of the act must be “fair” and “equal” (but how something so subjective is to be measured, we aren’t told). This is both dumb and dangerous. “Fun” is immaterial; this is the kind of argument used to stigmatize sex workers because we don’t have work-sex for “fun” or “pleasure”. The actual standard is, “Did everyone get enough of what they were looking for out of the encounter to be OK with it? And if not, was it because the other person was actually behaving badly?” There are lots of reasons for having sex, and “fun” or personal pleasure is only one of them. Just because it’s the only one you personally appreciate doesn’t make all the dozens of other reasons “bad” or “wrong” or “lesser”. Even people who do enjoy a sex act don’t necessarily enter into it “enthusiastically”. I know that I never do; being persuaded is a big part of the pleasure of sex for me, and I’m not remotely alone. And someone who needs to be persuaded is, by definition, not “enthusiastic”. Finally, even if the sex wasn’t everything you wanted, that does not automatically mean the other person was acting maliciously. Use your damned adult judgment, for Aphrodite’s sake; most people of both sexes are crap in bed, so bad sex is usually just due to the incompetence of one or both partners, not some eeeeeeeeeeeeevil plot on the part of one of them.
Furthermore, “enthusiasm” is a form of behavior characteristic of people incapable of actually considering all the aspects of a situation they find themselves in; it’s the elder sister of disappointment and the mother of resentment. “Enthusiasm” is what happens when hormones or neurology overwhelm considered judgment. It’s much more common in the young, whose brains haven’t completely stabilized yet. And while it can be intoxicating to experience, it’s unwise to make important decisions while intoxicated.