Ida Alice Flagler was born in 1848 and grew up in Philadelphia. Her father died when she was young, and her family struggled financially. Alice briefly worked as an actress before becoming a nurse for Mary Harkness Flagler, the first wife of businessman Henry Flagler.
In 1883, Alice married Henry Flagler. Henry was 53 years old and Ida Alice was 35. They went on a honeymoon to Jacksonville and St. Augustine, where they were inspired by the area and eventually built the Ponce de Leon Hotel in 1885. Their homes were Kirkside in St. Augustine and Satanstoe in New York. They also often used the yacht that Henry named after Ida Alice, the Alicia to visit Newport, Rhode Island, and other society locations.
Alice was very popular in St. Augustine and often hosted dinner dances attended by wealthy guests like the Astors and Vanderbilts. It was at one of these events that Henry Flagler met Mary Lily Kenan, who would later become his second wife.
In the 1890s, Alice became interested in Spiritualism and claimed to communicate with historical figures using an Ouija board. She also openly spoke about her husband's infidelity, which caused him to become concerned about her behavior. She also claimed that the Russian Czar was in love with her and that she would marry him.
In 1895, Alice was sent to Choate House, a sanitarium for mental and nervous disorders, after doctors were consulted about her behavior. She was diagnosed with "incurable delusional insanity" and stayed there for several months before undergoing a "rest cure" at the Flaglers' Orienta Point mansion.
However, Alice's condition worsened, and she was declared legally insane by the New York Supreme Court. The controversy surrounding Henry Flagler's divorce from his wife Alice in 1901 was mainly due to the fact that she was diagnosed with "incurable delusional insanity" and confined to a sanitarium, where she spent the rest of her life. At the time, mental illness was not well understood, and many people believed that it was a moral failing or a character flaw rather than a medical condition. Furthermore, the idea of divorcing someone for mental illness was seen as unethical by some, as it was believed that marriage was meant to be a lifelong commitment regardless of the circumstances. However, Flagler was able to get new Florida divorce laws created, which included provisions for divorce on the grounds of insanity, to end his marriage to Alice and marry his new wife Mary Lily Kenan.
Henry "did her right" in that he gave Ida Alice a significant settlement in excess of $2 million to provide for her care for the rest of her life. He often tried to help get her out of her confinement after his divorce. However, she never improved enough to be able to be outside of the hospital. Alice spent the rest of her life in isolation and died in 1930.