The Plastic Ono Band is a band formed by John Lennon and Yoko Ono in 1969 as a vehicle for their collaborative and solo projects. Lennon and Ono had begun a personal and artistic relationship in 1968, collaborating on several experimental releases. Following their marriage in 1969, they decided that all of their future endeavours would be credited to a conceptual and collaborative vehicle, Plastic Ono Band. The band would go on to feature a rotating lineup of many musicians, including Eric Clapton, Klaus Voormann, Alan White, Billy Preston, Jim Keltner, Delaney & Bonnie and Friends, and Lennon's former Beatles bandmates George Harrison and Ringo Starr.

By the beginning of 1973, recording had begun in earnest on Ono's next album, Feeling the Space, featuring a new group of studio musicians. The newest incarnation of the Plastic Ono Band featured guitarist David Spinozza, keyboardist Ken Ascher, bassist Gordon Edwards, percussionists Arthur Jenkins and David Friedman, saxophonist Michael Brecker, pedal steel guitarist Sneaky Pete Kleinow, as well as regular contributor Jim Keltner. The album would be released in November.  Throughout 1973, Lennon and Ono's relationship became strained. By August, the two had begun a period of separation that Lennon called "The Lost Weekend". Lennon began the recording of his own album, Mind Games, using the same players as on Feeling the Space, dubbed "The Plastic U.F.Ono Band". Around the time of the album's release in November, Lennon moved to Los Angeles with new lover May Pang. In October, Lennon began the recording of an album of rock 'n' roll oldies (a contractual obligation due to a lawsuit). These featured many Plastic Ono Band regulars (including much of the "U.F.Ono Band", Klaus Voorman, and the return of Phil Spector to the production chair), but upon release in 1975 as Rock 'n' Roll, it was credited to Lennon alone.  The sessions for Rock 'n' Roll were extremely troubled, and the sessions were abandoned until a later date. In July 1974, Lennon returned to New York to record Walls and Bridges. The new "Plastic Ono Nuclear Band" featured both old and new faces, with Jim Keltner, Kenneth Ascher, and Arthur Jenkins continuing from Mind Games, the returns of Klaus Voorman, Nicky Hopkins, and Bobby Keys, and the addition of guitarists Jesse Ed Davis and Eddie Mottau. Recording was finished in August, and the album was released 26 September and 4 October in the US and UK respectively.  Walls and Bridges would prove to be the last release of new material by the Plastic Ono Band in the 1970s. Lennon subsequently returned to his marriage with Ono and retired from music following the birth of his son Sean. The compilation Shaved Fish was released in October 1975, Lennon's last release credited to the Plastic Ono Band. Upon his and Ono's return to music in 1980 for the album Double Fantasy, they played with an all-new group of studio musicians who were not billed as any variation of the Plastic Ono Band name. Lennon was shot and killed shortly after the release of the album.

Using a quote from the above article, answer the following question: What does that mean
Throughout 1973, Lennon and Ono's relationship became strained. By August, the two had begun a period of separation that Lennon called "The Lost Weekend