Have you seen the Enemy(2013) by the same director?
In Enemy, the spiders mostly appear in dreams, or in dreamlike scenarios, suggesting a Jungian approach to their interpretation. On the one hand, spiders are frightening and dangerous; on the other, they have a direct connection to femininity… the spider connection seems to stem from a different system of thought: the Freudian Madonna-whore complex, in which men see women as either saintly mothers or worthless sex objects. The spiders are implicated early on in the film in some sort of sexual rite, and when Helen, a pregnant woman, turns into the spider after having sex with Adam — shortly after Anthony cheats on his pregnant wife with Mary — it could be seen as a literalization of Adam’s disturbed psyche, which can’t handle intimate relationships. Enemy appears to say that even though Adam has done away with Anthony — and Mary, an innocent bystander who represents some sort of purely sexual relationship, in the process — he still has a ways to go before he can reconcile these two facets of womanhood. And note the names: Mary, the mother of Christ; and Helen, the catalyst for the Trojan War. There’s also a motif around high heels, an obvious feminine symbol: Adam and Anthony each notice Helen and Mary’s heels at separate points in the film, and the platform heels used to crush the spider at the beginning are, uh, hard to miss.
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https://www.vulture.com/article/enemy-movie-ending-explained.html