A family of Microsoft word processing software products for creating web, email, and print documents.
To Word, all non-heading text following a heading belongs to that heading. What you could do is add a blank paragraph immediately before the "unrelated text" paragraph in your example and format that blank paragraph in, say, Heading 1 style.
Note that this is a bit of a clumsy workaround. In general, it is better to avoid blank paragraphs in a document.