Louis I was suo jure

Suo jure

Suo jure is a Latin phrase meaning "in her [or his] own right".It is commonly encountered in the context of titles of nobility, especially in cases where a wife may hold a title in her own right rather than through her marriage....

Count of Nevers and jure uxoris

Jure uxoris

Jure uxoris is a Latin term that means "by right of his wife" or "in right of a wife". It is commonly used to refer to a title held by a man whose wife holds it in her own right. In other words, he acquired the title simply by being her husband....

Count of Rethel.

Louis was the son of Robert III, Count of Flanders, and Yolande, Countess of Nevers. He succeeded his parents as Count of Nevers. In December 1290, he married Joan, Countess of Rethel

Joan, Countess of Rethel

Joan of Rethel was Countess of Rethel between 1285 and 1328.She was the daughter of Hugh IV of Rethel and his third wife Isabelle of Grandpré.She succeeded her father as Countess of Rethel in 1285....

, and thus became her co-ruler in the County of Rethel. They had two children:

• Joanna of Flanders
  Joanna of Flanders
  Joanna of Flanders , also known as, Countess Jeanne, Jehanne de Montfort, and Jeanne la Flamme, was consort Duchess of Brittany by her marriage to John IV, Duke of Brittany...
  
  
• Louis I, Count of Flanders, Nevers and Rethel

He died in Paris

Paris

Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

 shortly before his father and thus never succeeded his father as Count of Flanders.