This tacitly implies that women are sex objects and that men only seek them out as such. I find that offensive, but more so than that, sad.
You'd also have to prove that online dating has 'caused' this effect, and what you've posted is a complete lack of evidence, at best.
It could simply be that many women have better career options and don't have to settle for early marriage to whichever man in a bid for financial security and social acceptance, or changing attitudes towards more casual sexual encounters, or a number of other things.