They emerged from the tunnel and were on the airport highway, with its lights on both sides attached to tall standards. Witty had watched Hardy operating the automobile at first, and had not spoken. He began to play with Yolanda, who was on her mother's lap, before they reached the airport highway. The three adults on the back seat were amused as Yolanda played enthusiastically with her uncle's animated fingers as he reached back over the front seat.
Hardy was completely absorbed with the driving and maintained his speed just below the posted limit. He wished he had known Nancy longer, and he could be sure that he was in love with her.
Perhaps they might be married by this time. He would kiss her for the first time before she boarded the plane bound for California. [The italics are mine.]
His previous thoughts about her had not been desirous, although he was sure they would have soon become lovers. “When she and Mamie and Albert reached California, she promised to send him their address, and he told her that he would be out there very soon. It did not seem proper, somehow, for him to tell her of his secret plans to marry her, so he did not mention it. How would she look when she became pregnant, he thought.
They would have one other child with Yolanda. Nancy's figure was beautiful, and he would have it distorted only once with pregnancy. This would be for their son. [The italics are mine.]
Quid Pro Quo -The Story of a Riot and the Cleavage By David McIntosh
If we set the narrative time as the present tense, the sentence in the fourth paragraph would be:
His previous thoughts about her was not desirous, although he is sure they would have soon become lovers.
I don't understand why the counterfactual 'would have become' is used here. Soon has a past future time reference here, why not just say "although he was sure they would soon become lovers" instead?
Secondly, the past tense verbs in italics in this passage are clearly in free indirect discourse; they narrate the train of thought in Hardy’s mind, which could be otherwise represented in direct speech as:
‘We may/might be married by this time. I will kiss her for the first time before she boards the plane bound for California.’
‘We will have one other child with Yolanda. Nancy's figure is beautiful, and I will have it distorted only once with pregnancy. This will be for our son.’
Since by this time has past time reference, I think the quoted sentence should be "they might have been married by this time" rather than "they might be married by this time". Why did the writer use the bare infinitive form over the perfect infinitive form?