Sexual fluidity is in the air…or is it sexual flexibility ? Earlier this year, dating app Feeld named “ heteroflexible ” today’s fastest-growing sexuality, citing a 193 percent increase in use of the label among Feeld daters last year. To identify as “heteroflexible” generally means to consider oneself primarily straight, with some level of interest in queer or same-sex experiences. The Feeld report interprets the rise of heteroflexibility as a sign that “curiosity is becoming culturally acceptable” as young people “experiment at the margins of their existing identity,” suggesting an increasing societal understanding of sexuality as dynamic rather than fixed. But while heteroflexibility may be having a moment, it’s not a new term. In fact, it may strike some as a bit of a dated throwback to an arguably less sexually fluid era.…