Kick Jesse out, don't waste time on Dan in jail or info on the hospital/Lincoln group. Just have Sarah and Lester alone for a chapter. Have lots of eye contact and dialogue. Speak explicitly about their desire for each other. Have Sarah express her love for Lester without prompt. If they're going to spend the night at the hotel, then talk about that. Don't just fall asleep. Have Sarah say she feels safe and comfortable in his embrace and promise that she'll choose Lester's room while they're in Chicago. Don has mentioned many times that Sarah is addicted to Lester's smell, have him find out about that and use that to deepen his hold on her.
If Don was serious, he'd dedicate the entire chapter to Sarah and Lester. Just fucking and talking and making love. Lester would extract more demands from Sarah and she would become even more submissive and affectionate to him. Then having established a new stage of their relationship, the revelations about Dan would happen, Lester can resolve it by lying and convincing Sarah that it was an innocent mistake. Dan, baffled at his wife's trust for Lester, would go along with it as a long term plan to expose and rid themselves of him.