Singleness: Temporary? or Semi-permanent?

Mid-thirties Jane is invited to a girlfriend’s family reunion. One family member, a new Mom was carrying her newborn & she looks at Jane as the wind blows out her dress to make her appear pregnant. Jane catches her suspicion & flattens the front of her dress at the waist to show her non-prego status. Some time passes, lunch is served, & everyone is enjoying friendly conversation. Jane turns to new Mom to ask about her darling newborn, and the following dialogue unfolds:

New mom: “So, are you dating anyone?”
Jane: “No.”
New mom: “Why not?”
Jane: “Waiting for the right one.”
New mom: “Aoh… you’re so pretty… What’s wrong with you?”

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Now I realize New mom’s last statement seems insensitive but to be honest, I've had the very same inner-monologue happen in my own head about an attractive, unmarried woman over 30.

Why do women treat singleness like a temporary state to hurry out of?