Here’s the whole fantasy. You are at the doctor’s office. Or at work. There is a pretty young woman there. That alone: fantastical. She is not looking at her phone, grunting cruelly at some other guy’s text. She does not have a boyfriend. She looks at you. You are not invisible to her. Not innately puke-inducing like a silverfish found in her panty drawer, hauling its unwieldy H.R. Giger chitin sperm casing between wispy twitchy legs and trailing a six inch smear of dust and hair from under the refrigerator. An attractive woman a) exists in the same place as you b) acknowledges you. c) does not recoil and cry out for some other guy, her boyfriend, to come kill you with a magazine you while she hides her eyes, and later she’ll tell the story of the ugly silverfish in her drawer to her colleagues, wail on facebook, make an accusing phone call to her landlady.
A pretty girl who does not have a boyfriend a) exists, and b) thinks things, and says them; she speaks and then you are having a two sided conversation. Not just you digging into the terrified cavernous emptiness of your adrenalized OH FUCK A PRETTY GIRL head for a perfect thing to say, voice cracking like Peter fucking Brady, flailing to drag it out past her first sentence when it becomes clear she never thinks about anything. Or if she does, it’s dogs, or astrology. She talks to you and wants to know you and plays you some nice music and you keep hanging out and between now and when she becomes your girlfriend none of the fifteen billion other men on Earth get in her face with a better proposition, and suddenly your texts go unreturned for long painful eons, and the desperate agony makes you repulsive to her like a gangrenous wound. To her, and all other women.
Every day you are a worm dying on the sidewalk after the rain. The Manic Pixie Dream Girl picks you up and tosses you back on the grass. She’ll leave you. That’s part of the trope. But all you needed was just once, a nice pretty girl talks to you somewhere. You got a better shot at crapping out the crown jewels.