They were married when she was 18, on October 6th, 1760. Joseph was extremely happy with his new bride, and quickly fell in love with her. Isabella suffered from an obsession with the idea of dying young, after her mother had died a year before the marriage. As such, she would often isolate herself from her husband, out of fear of physical intimacy leading to pregnancy, convinced it was going to kill her.
After a difficult first pregnancy, she gave birth to their only child to survive past infancy, Maria Theresa, on March 20th, 1762.
Isabella suffered a miscarriage in August of that same year, and a second one in January of 1763. She became pregnant again quickly, but contracted smallpox and gave birth three months premature to a daughter, Maria Christina, who died hours after birth. Isabella herself died a week later, and Joseph never fully recovered from her death.