Applying any sort of logic to NTR (except the ones which help ) defeats it's purpose .
The story is simply about two people now. Sarah and Lester .both these characters are interesting in their own and together .
At first it was about dan too but as Lester came in foreground .dan has diminished as a character. He has already been cuckolded and emasculated . his character arc is boring to read unlike Corey from "Ascending Lauren ".
My unpopular opinion is relegating Dan in background while Lester and Sarah revel in their relationship for a few chapters .
Also Dan and Sarah's marriage should remain intact cuz breaking it will also defeat the story's purpose . It was never about their marriage
Lester can always be her one "true" love while Dan will be the father and husband who ocassionaly visits his family . Dan's ultimate punishment will be loosing the passion he hoped cuckolding will bring in their marriage
We have to remember in "Ascending Lauren", the characters Corey and Lauren are much older than Sarah and Dan, their children are already adults, unlike Sarah and Dan's daughters who are still children and are totally dependent on adults. Sarah's corruption goes through this too, destroying Sarah's mother, and this impacts the husband and wife relationship (Dan was pissed when Sarah practically forgot about her daughters at school). Lester also has a different profile than Alex. And let's be honest, Lauren didn't leave her husband for Alex because it's a fictional story, the emotional betrayal, the detachment and the lack of love are clear in the story, she loves Alex and likes to humiliate her husband. I don't know how Lauren didn't have sex with her own daughters or have an orgy with Corey's 3 women and completely destroy him. Corey is 61 years old and Dan must be around 30, Corey can't get an erection because he's old, unlike Dan. Besides, in Corey's case, he could do a TRT (regain more strength and youth, he has money). While Lauren made Corey eat sperm from her hands, Dan has these realities as his fears, darker and Sarah doing this to him will destroy him, it would be Lester's final victory and the end of the relationship. (Note: I'm Brazilian, we have a different culture than people in the US, who have an easier time discarding what they don't want), that American life profile. Dan doesn't stay with his wife, doesn't have normal moments as a couple or with his family, doesn't have sex, doesn't talk to his wife and daughters for weeks "not even on the phone". So it's normal for him to take the team off the field and the marriage to end, or for him to have a fit of rage and end up killing Lester and going to jail and Sarah ending up as a prostitute (and it's dangerous for you to take people to extremes). And what kind of love is this person? It is not part of their daily lives. They are only remembered to be humiliated and forgotten. They are betrayed beyond sex. Their wives spend only a few minutes with them. It gets complicated. There is no way they can stay stuck in this drug forever. When their daughters become mothers? They will not have a normal set of grandparents. The grandmother is a whore who only enjoys sex and the grandfather is clueless.
For Dan and Sarah's children to be left out of the story, they should not have such children. This is the real problem with children, because they will always be there, until they are independent.