Substantial conflict related to how to respond to and fit into the domestic sphere is a recurring issue in Plath's writing, suggesting this was an issue she struggled with in her real life. A small part of her seemed to buy into and even desire a fairy tale marriage, but a larger part of her seemed to bitterly realize that she was not the type who could ever fill the role of wife successfully, because she could not help but to perceive the role as docile and vapid and otherwise weak and she could not help but to disdain and despise such traits, as well as the men who covet them.
If one reads 'The Applicant' and thinks of the applicant as a man applying for a wife, notice how the descriptive language in the first two stanzas of the poem presents this man as weak, sniveling, crying, needy, and unworthy of respect.
Of course, Plath also harshly derides the role of wife or at least the generic clichés and conventional expectations associated with being a docile helpmate, almost like some kind of walking, talking appliance. In this poem, the wife seems to be given no sense of agency or individuality. She is presented as a semi-generic product that is expected to embody certain functions; if she does not, then she can be fixed or replaced, because products are interchangeable.
What is not so interchangeable is the sense of finality associated with the poem's repeated question, 'Will you marry it?' The repetition of this question within the context of the less than pleasant descriptions in this poem seems to convey a certain sense of dread about marriage- a binding contract that is more about products and their functionality than about individual people.
The poem presents the marriage contract as largely non-negotiable. The applicant doesn't have a voice in this poem, doesn't have a say in the matter, and even though she/he is being offered a presentation of a proposition that would seem to include the option of either agreeing or disagreeing to the proposition, she/he is basically being informed that this is the only choice.
Notice that by the poem's final line, the repeated question, 'Will you marry it, marry it, marry it', although still seemingly phrased as a question, no longer has a question mark at the end. It now ends with a period, essentially turning it into a declarative statement or a pronouncement that is just pretending to be a question.
Over the course of the poem, the pitch to the applicant has shifted from soft sell to hard sell, underscoring the finality of the poem's unpleasant perspective that whether or not the applicant personally likes the services (generic helpmate traits), the product (wife), or the contract (marriage) being presented, abandoning this set of roles or revolting against the contract is not an option.