Final answer:
The duration of Sykes and Delia's marriage is not specified in the provided texts, and one would need to reference the story 'Sweat' by Zora Neale Hurston to find this information.
Step-by-step explanation:
You have asked about the marital duration between Sykes and Delia, which is a question related to 'Sweat' by Zora Neale Hurston, an important piece of African-American literature.
Unfortunately, this information is not provided directly in the available texts.
To answer your question accurately, one would need to refer to the story itself. In Hurston's 'Sweat', the issues of domestic abuse and marriage are central themes, and the dynamic between Sykes and Delia reflects the complex and often painful experiences within abusive relationships.
In other literary examples, such as the marriage between Joe and Louisa in 'A New England Nun', which lasted 15 years, or the engagement period of Dexter and Irene in F. Scott Fitzgerald's work, the length of relationships can be critical to understanding character development and plot progression.