In advice columns and normie discourse, the concerns men have about sex decreasing in a relationship are met with the trope "Sex ebbs and flows in a relationship. Don't worry, things will get better after $event". ($event== home renovation is finished, kids go to kindergarten, kids go to college, therapy is finished, whatever). This is gaslighting on par with "just be yourself". While month to month sex surely varies somewhat ("ebbs and flows"), the overall trend you see in /relationships, /dead_bedrooms, etc is sex declines after $event to a new much lower normal. Sex doesn't ebb and flow, it just ebbs, usually after particular discrete events. Often the events are the moments where the man commits more to the relationship.

Events that seem to often cause women to permanently give less sex to their men:

  • Moving in together
  • Getting engaged
  • Getting married
  • Buying a house together
  • Having a kid (this is the big one)
  • Menopause

If the true curve of sex supply in a relationship was known to men, as well as the common triggers (committing and doing the stuff women want), fewer men would want to be in long-term relationshits (especially marriages with kids and houses).