Complex sentence: Very little is known about Elizabeth Wykes, or her marriage to Thomas Cromwell, a problem made more opaque due to the fact that she died early in his career at Court, long before he reached his zenith.
Split into simpler sentences: Very little is known about Elizabeth Wykes, or her marriage to Thomas Cromwell. A problem made more opaque due to the fact that she died early in his career at Court, long before he reached his zenith.