Cynthia Lennon, the first wife of the Beatles’ John Lennon, who chronicled their troubled marriage in two memoirs, died on Wednesday at her home in Mallorca, Spain. She was 75.

The cause was cancer, according to a memorial on the website of her son, Julian.

Ms. Lennon, then Cynthia Powell, met Lennon when he was a student at the Liverpool College of Art in the late 1950s. She was a studious, proper young lady, in stark contrast to him.

“He was a total rebel, and everybody was amazed by him,” she said in a 2005 interview on ABC’s “Good Morning America.”

She ended her engagement to another man, he broke up with his girlfriend, and they began dating. It was during this period, Ms. Lennon said, that she first dealt with his jealousy and anger. She said that he smacked her in the face for dancing with another man, after which she broke up with him for several months.