I did not get that from the story - .....
that Max De Winter wanted to kill his wife for any reason. Rebecca had been flaunting her affairs to Max for some time, especially her affair with her cousin. When Rebecca found from her doctor she had an incurable cancer, she goaded Max into killing her. This would be her ultimate revenge: Max being tried for her murder. In the movie, Hitchcock had to change this a bit. Rebecca commits suicide, but angles it so it looks like murder. The Hollywood censors would not permit Max to go free if he did kill Rebecca, even though she goaded him into it.
The second Mrs De Winter and her husband Max do not seems dysfuntional to me. Just entirely human. A man can only take so much from a person as self-centered as the evil Rebecca. Rebecca knew this and essentially perpetrated her own death.
You are, of course, entitled to your opinion ....
but your opinion differs greatly from how Daphne Du Maurier's story influenced this reader. Maxim didn't kill Rebecca simply because she told him she might be with child. He killed her because she goaded him into it, teeling him she could provide a heir to his beloved Manderlay and there was nothing he could do about it. It was more a matter of manslaughter, not a premeditated murder. And she really wasn't pregnant. Rebecca wanted him to kill her.
The second Mrs. De Winter was in love with Maxim. She knew the evil of Rebecca. She says, in fact, Rebecca can't hurt me any more. The fact that Maxim shot Rebecca was tragic to her, but she realized how far Rebecca had pushed Maxim. She knew it was now all over, and Rebecca couldn't hurt her or Maxim again.
I wont further try to change your mind, but having seen both movie of Rebecca, the 1940 one and the BBC one, the directors of both understood Du Maurier's book to be the tragic story of how an evil woman can ruin lives. You should see them.
You keep talking about an unreliable narrator ....
but in actuality the narrator is Daphne Du Maurier speaking through one of her characters. The naivity of the second Mrs De Winter makes her story ring true. Consider the following:
1. For months, even years, since their marriage, Rebecca had had illicit affairs and trysts at her beach house. Her affair with her cousin was especially loathsome to Maxim since as her near relation he had the run of Maxim's house. Socially, Rebecca was the beautiful wife of the handsome Maxim de Winter. Privately, she was an adultress who flaunted her affairs to Maxim.
2. When Rebecca returned from her London doctor, she knew she had terminal cancer. In 1938, there was no chemo-therapy or other treatments other than intrusive surgery. Rebecca hated Maxim. She probably hated most men with the possible exception of her cousin who was about as corrupt as Rebecca.
3. She decided to goad Maxim into killing her. She knew that flaunting her affairs wouldn't do it. Maxim ignored her infidelities primarily because of his social status. And he no longer slept with Rebecca.
4. So she announced she was pregnant. Maxim knew it wasn't him, but he didn't know by whom. Then she reiminded Maxim that his estate was entailed. This means that by law, the estate would be inherited by Rebecca's child. This meant that his beloved Manderlay would someday belong to Rebecca's child, even if he remarried and had other children. This entailment would have been a part of the marriage contract. Before Maxim knew what Rebecca was like.
5. This was the last straw for Maxim. He did what Rebecca wanted him to do: he killed her. Rebecca committed suicide as sure as she held the gun herself. She didn't know that Maxim would find such a unique way of disposing of the corpse. She thought Maxim would be tried and convicted of her murder and subsequently hanged, which was a pretty sure thing in those days.
6. You have to understand 1938 British law and what entailment meant. Manderlay was not just a house. It was an estate, and judging from the French name De Winter, it had probably been in his family since shortly after the Norman invasion.
7. When Mrs. Danvers burnt down Manderlay, it released the De Winters from the any hold that Manderlay had on Maxim. They were now free of the past. Maxim was not a Bluebeard. The new Mrs de Winter knew he wasn't a killer. She was in love with him and knew he would never kill again.
This is a very psychological novel. I think your misunderstanding of it stems from not being cognizant of entailment and British law. And by the way, Rebecca was never pregnant. This was said to make Maxim pull the trigger.