See this WaPo article and specifically the chart titled "Young men driving the decline in sex": https://www.washingtonpost.com/business/2019/03/29/share-ame...

It dances around the point but the GP's logic seems plausible, if exaggerated. If the increase in sexlessness among young men is ~twice that of the increase of sexlessness in young women over the same timeframe, it is quite plausible that the same men are having sex with more women.