Carol situation is a case of prisoner's dilemma, which may be presented in a bit shorter way than the article does. Let's use standard game theory terms for the possible actions of one male individual:

'Cooperate' (C) = to publicly approach an attractive girl

'Defect' (D) = to ignore the girl, read the paper instead

So, imagine yourself walking into a cafe and seeing Carol at a table. She has been there for a while, and you have no way of knowing if some other guy has already approached her (or if Carol has a boyfriend). Let's assume for the sake of simplicity that the first man who dares to approach Carol always gets her telephone number (her nice way to reward him for being brave). That automatically means that the second guy will be rejected and feel bad.

The outcomes are (in order of preference):

CD = You dare to speak to Carol, you are the winner, the other guys didn't dare to approach her.

DD = Every man in the room reads the paper, Carol sits alone.

DC = You choose to ignore the girl, then some lucky bastard walks across the room and gets her number. Bad, but you have not lost your face.

CC = The worst outcome. You have approached Carol, but she is already involved with someone else. You walk back to your table, feeling miserable.

You notice that second and third outcome are somewhat identical, there is no gain, but also no real damage. A rational person may well prefer to do nothing and land in the 'neutral' area where 50% of total outcomes lay, rather than to approach Carol and to have 25% chance of success vs. 25% chance of a complete disaster.

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I think it is not the women's attractiveness that acts as a repellent, but uncertainty of her status (has or has not a partner already). The way for Carol so improve her situation is to develop some sort of signalling that says she doesn't mind to be approached (flirting used to do the trick in old times).