If you want to blame someone, blame all those "when sex???" fans, I personally still like the story but it's clear that at some point (around issue 4 or 5) the hesitation of the mom disappeared because fans kept asking Mando to "rush the development" and give us sex scenes already, I really feel that the whole "one of the guys at work let his wife and son fuck, I'm not into that but now, suddenly, that's hot!" was a bit dumb, but it was that or something repetitive like turning the dad into a cheating asshole.