Ok, I have really thought about this and am not so disappointed in the last chapter as I am in Don and his planning, within his writing (outline, reasons and hints as to something being built up to, within a story, etc.).
I am a huge fan of the psychology within a story. I just don't want to know why someone does something but why and how deep does earlier mental trauma/exhuberances affect the changes and choices made. I have been reading this as a surface story, the way I generally read most porn that I read, but this chapter changed things, deciding to make this a psychological study/story of a svengali brainwashing a mark, for lack of a better term. I just wish that Don had laid some breadcrumbs leading here, because up until this chapter this was a big dick, horny woman, cuckold kind of story.
The story in truth is that of Lester taking women and working to change their psychology and belief structure through the use of his dick, sex, and the very leading instructions he gives them. With Sarah, he not only met the woman he thought epitomizes the way women should look, but an independent woman, who he saw as the ultimate challenge to put her in her so-called place. It seems that he is trying to change Dan and fuck that, Dan is an obstacle and nothing else. Yes, he wants Dan to hate himself as he sees Sarah changing, but he really doesn't give a shit about anything, except him getting the fuck out of his way, the way, he feels he is owed. Recently, there have been a slew of men attacking women for anything from wanting control over their own bodies, to making their own sex choices, to even voting. Lester would be the president of this, but only to use the men he empathizes with as means to get more women to personally control.
I no longer believe that Lester wants to marry Sarah, or to take over her family, or even to win over her kids. He sees all of that as obstructions to his true goal: change Sarah's brain using sex and reinforcing patterns of speech and using her primary point of her personality to that goal. He wants her to ignore and despise Dan, seeing him as weak. He wants her to want to give up her children for him, as they are in the way of him controlling Sarah. He wants her to think that it is all her own idea, like suddenly supporting the idea of helping in Jesse's revenge against her husband, by letting him fuck her and fucking him back and cumming inside her, knowing that it would "break him" when it happened. Her phone went off and will continue to do so every now and then, depending on when Cook county allows him to make calls. Lester may even let her listen to Dan's voice mail, as he will then demand she decide whether to save Dan or fuck him. Lester will continue to re-pattern her brain through sex and manipulation. He will remind her that he said the two of them, a stranger as punishment, and no Dan's allowed. Sarah agreed. He will even admit he got Dan arrested so he could sit in jail while he fucked his wife and that he was tired of interfering with them and what they had. He will make her look at his engagement ring, a ring -- like his cock -- bigger that anything Dan could ever give her. Lester will tell her to make a choice. Show him her choice by destroying her birth control pills and having his baby while Dan sits alone, behind bars.
Don will have Sarah's brain bent and she will choose Lester for that weekend and eventually get Dan out, telling him that he being in jail is his own fault. I bet she will take Lester's side in ever-increasing arguments and will invite Lester to stay at the house - while she sends Dan's spawn to her parents. At Lester's insistence, she will occasionally invite Jesse to the house so he can fuck her in Dan's bed, to show him how much better than Dan he actually is, but never as good as Lester.
When she does become pregnant, that will be the end of Sarah and Dan, as her training and brainwashing will be completed and the new couple will be Sarah and Lester.
Sorry for the length, but it is hard to make an argument like this without evidence and there is plenty that now is coming to light but Don hid for far too many chapters and months. It's kind of like the mysteries that wait until the end to tell you everything. The best mysteries will feed you small clues throughout, that you may not even get at the time, but when you finish the book, you feel a little embarrassed and maybe a little stupid as you can now see that you should have known all along. We couldn't have possibly known any of this all along.