Downton Abbey-Cora's Predicament

Born Cora Levinson was the only daughter of Martha and Isidore Levinson. She had a brother Harold Levinson. Cora was brought to London as a young Woman for her first season by her socially ambitious mother in order to marry a member of British nobility. She met Robert Crawley, Viscount Downton and future Earl of Grantham. Cora became engaged to him and they married on 16th February 1890. They later went on to have 3 Daughters Mary, Edith and Sybil.
Years later Cora and Robert have been married for a long time. Their relationship seems so what strained. It doesn't help their relationship by the arrival of Art Historian Simon Bricker. Aware of Simon's flirtatious behavior Cora enjoys the attention however Robert looks on in disgust. Cora starts to have feelings for Simon but forever tries to deny them. How long can Cora carry on denying them? And how long can Robert go on with Simon's constant presence?.