Henry arranged betrothal to Isabella of Gloucester, but only after disinheriting her sisters so that all Gloucester lands would be hers on her father's death. This was in 1176, when John was nine and Isabella was only three or four years old. Both were great-grandchildren of Henry I, meaning the marriage was forbidden due to the laws of consanguinity. The wedding did not take place until 29 August 1189, at which John became Earl of Gloucester.
The Archbishop of Canterbury, Baldwin, placed the Gloucester lands under interdict—meaning no one living there could partake in any Catholic services—due to the violation of consanguinity laws. An appeal to (antipope) Pope Clement III for a dispensation. This was granted, on the condition that the two abstained from sex. This explains why 10 years of marriage produced no children.
John pursued the consanguinity prohibition when it suited him—which it did after he became king. Wanting an heir, and not being interested in having them with Isabella, he annulled the marriage on the grounds of too-close blood ties. He put Isabella in "honorable confinement" at Winchester with an allowance for her comfort. John's lack of sensitivity to the feelings of others—and, after all, there is no sign that he cared for Isabella at all except for the political advantage—had a "task" for her. When John re-married, to a twelve-year-old Isabella of Angoulême, he lodged his new bride at Winchester in the care of his first wife, increasing her allowance from £50 to £80 pounds because she was hosting a queen. The second Isabella stayed with the first until a few weeks before she gave birth to the future King Henry III.
Eventually he found a new marriage for Isabella: in 1214, the Earl of Essex, Geoffrey de Mandeville paid to John 20,000 marks for the privilege to marry Isabella. He was a much younger man, but he died two years later. Unfortunately, because at the time of his death he had been rebelling against John, John confiscated all his lands, which included Isabella's Gloucester lands.
Now a poor widow, she married again a year later, to Hubert de Burgh who became the Chief Justiciar under John and John's son, Henry III. Sadly, she died only a month after marrying Hugh. She was interred in Canterbury Cathedral.
Now, about that second wife also called Isabella: let's learn more about her next.