A note: using that standard, properly modified, you can't prove that the existence of the sex drive is an objective phenomenon. Your challenge seems loaded.
If it's "loaded," it's because of the claim that happiness is an objective property: "of, relating to, or being an object, phenomenon, or condition in the realm of sensible experience independent of individual thought and perceptible by all observers : having reality independent of the mind ..."
Nobody denies that "happiness" is a real thing. The question is, rather, whether a state of happiness satisfies the criteria of objectivity.
Similarly, nobody denies the existence of a sex drive. But it is not a completely objective thing, either. Consider: Most guys don't want to have sex with every woman they see, and they don't even want to have sex all the time. The criteria for what makes you want to have sex with one woman and not another ... or now but not yesterday ... those are bewilderingly complicated, to say the least, and they're different for different people.
It's not enough to note the objective fact that there's a sex drive, or a human capacity for "happiness," however defined; the thing is that it operates on highly subjective criteria.