Somewhat along the lines of your first few points (changing dynamics between men/women) and your point about testosterone... as a early 30's male, I've noticed a dramatic change in the dating scene over the last ~8years w.r.t. meeting women that are worth 'bringing home to the fam'. [i.e.-God fearing women that have solid values and aren't asleep.]

Couple that with the fallout of the #metoo nonsense where more men (non-ladyboy types) are genuinely fearful their lives will be ruined by a consenting date making false accusations in a Guilty-Even-When-Proven-Innocent climate.

Then the hormone/depressant/mental health component which absolutely is a worsening factor, especially in younger generations as it precludes healthy relationships conducive to making rabbits.

The transition to 'online dating' which is really just a cesspool of bots & Jezebels, not wholesome men/women for committed relationships.

Needless to say - I believe there is a 'Cultural Sterilization' component to this that is widespread and often overlooked.