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There's some truth to this argument--the problem is that, like with genetic arguments, the complexity of a person's intent is greater than a single motivating factor.
These kinds of theories also insist on demarcations based on binary thinking, demarcations that are often unnecessary.
Of course, I am about to make my own theoretical argument, but it is genderless: Namely, the essence of all romance, no matter the writer or the protagonists, is the desire to have another person in one's corner.
This desire is incredibly consistent. And surprisingly old. Imagine Penelope staying true to Odysseus by weaving a cloth, only to unpick it every night. Consider that Shakespeare's Petruchio and Kate still manage to capture modern viewers' affections--despite extreme gender-based arguments--since in the end they are more like each other and more likely to defend each other than anyone else. (The difference between Shakespeare's comedy romantic couples and his tragedy romantic couples points up this difference: the tragedy couples--including Romeo & Juliet--don't seem to know what they are trying to defend. And aren't very good at it.)
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Some authors will go on to discuss the line--as Dorothy Sayers does in her mystery books--between enjoying a person in one's corner and enduring a hovering crazy-person who stalks one's every footstep.
But the general consensus is that having someone say, "I'm on your side" is the ultimate aphrodisiac. In Andrew Grey's Best Worst Honeymoon Ever, the new (better) boyfriend doesn't take over the confrontation with the faithless ex-fiance, but he does make his disgust at the faithless ex clear. In Eden Finley's Deke, the journalist boyfriend Lennon confronts Ollie's loving but clueless family with the reality of "coming out" in sports. He says for Ollie what Ollie has struggled to say for himself. As far as traditional romances are concerned, Darcy doesn't properly move into "I'm on your side" territory until he ignores his aunt's criticisms.
You get me and you've got my back is the essence of good romance.