For most people with wives/girlfriends sunday morning is peak incidence of romance time.
Unfortunately, marathon training (or indeed most distance training) involves the sunday long run immediately afterwards.
Comparing 20-30k runs both post-coitus and without coitus there's a definite difference in training quality.
Can't reasonably say "no" as a man due to standard unequal societal pressures/expectations that men must endure in silence daily.
I'd imagine this affects many on here during marathon training blocks?