Final answer:
In the novel 'The Virginian,' a turning point in the protagonist's relationship with Molly is when he decides to secure a competency before their marriage, indicating the depth of their commitment.
Step-by-step explanation:
The major event that marks a turning point in the Virginian's relationship with Molly occurs when he announces his determination to venture into new fields to secure a competency before they should be married.
Despite the engagement and the prospect of a lengthy separation, Molly listens and consents with serene acceptance to the Virginian's plan. This decision distinctly outlines the depth of their love and mutual respect, setting the tone for their relationship as it defined by sacrifice and a test of endurance over time.