“There is much confusion in secondary sources concerning the order of the Robert’s two marriages. His first wife, whom he married circa 1487, was Katherine Marowe (c.1459-1503), the daughter of William Marowe (c.1419?-1464/5), Lord Mayor of London and three times Master of the Grocers’ Company, and his second wife, Katherine Rich. Robert married secondly, Elizabeth (nee Baynham) Russell, the daughter of Thomas Baynham (b. c. 1422, d. 16 February 1500) and Alice Walwyn (d. 10 October 1518).”
From the profile of Sir Robert Throckmorton, of Coughton
I think your disconnect was wrong.
Elizabeth Throckmorton Married 1) Robert Russell, of Strensham 2) Sir Robert Throckmorton, of Coughton
What makes you think they were not husband / wife?