Complex sentence: In the mid 1960s, Buck increasingly came under the influence of Theodore Harris, a former dance instructor, who became her confidant; she had met him in 1963, when he was working for the Arthur Murray dance studios.
Split into simpler sentences: In the mid 1960s Buck increasingly came under the influence of Theodore Harris, a former dance instructor, who became her confidant. She had met Harris in 1963 when he was working for the Arthur Murray dance studios.