Then I found it: an interview with the woman who coined the term "incel." It was on the Reply All podcast, and Alana, a queer Canadian woman explained that she had struggled all her life to find romantic and sexual partnership, and jokingly started referring to herself as "involuntarily celibate," and then, as an "incel":
https://gimletmedia.com/shows/reply-all/76h59o
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