People have limited time & energy, so some percent are conceivably putting less effort into the difficult ways of relieving sexual tension (relationships) while favoring the easier ways to do so (pornography).
Porn has been one of the first industries to take advantage of technology, and the change in accessibility of porn is unparalleled. It went from something one was forced to sneakily travel to shady locations and physically purchase to something that we are accidentally exposed to or even advertised to on omnipresent screens everywhere in our lives.
And that isn't even going into the way the market has selected for 'more potent' forms of pornography- like the way that just about every fetish can be explored to depths that would shock/offend someone who doesn't share it. (something that probably has an isolating effect on relationships)
And it also isn't accounting for the new-ish industry of 'relationship replacement' style streamers- another economic activity that I believe must be competing with traditional 1 on 1 relationships.