She died of the genetic heart disorder that killed her son and grandson, Thomas Teller. After the death of her son, Nathaniel, in 1975, she and Nate bought a home in the country and tried to create their own paradise, unfortunately smothering Gemma with unwanted control over her life. Gemma rebelled against her and was the cause of her leaving at the age of 18 and subsequently, meeting John Teller and becoming pregnant. Rose's biggest regret was losing Gemma in her life and they never repaired the wound between them.
Rose was a domineering and controlling woman, who displayed OCD symptoms, (her china figurines needing to be perfectly faced) and was an overbearing mother, who tried to control her children's lives. Her genetic heart disorder that runs in her family, had killed almost all her mother's side of the family and she dreaded losing her own to it. After her son, Nathaniel's death in 1973, she had them move to the country, believing it was to help save her daughter's life, but ended up driving her way, trying to control Gemma's growing desire to have freedom.
She died shortly before the start of season three, leaving Nate in the care of a live in nurse named Amelia Dominguez.