Conversation so far:
Who is Peter Green?
The band's first album, Peter Green's Fleetwood Mac, was released in 1968.
Did it do well in sales?
CANNOTANSWER.
Was it well received by fans or critics?
the band toured the United States for the first time, though Green was reluctant to do so for fear of gun crime.
Upon their return, they recorded a second album.
Are there any other interesting aspects about this article?
Green himself drifted away from the band, struggling both creatively and with increasing use of LSD.
Did he ever return to the band?
He pulled out of the mainstream and chose to stay at home.
He doesn't play much anymore.
Who was he replaced with?
CANNOTANSWER.
Did Green leaving cause issues with other members?
He doesn't play much anymore, which is certainly a shame, because he's my mentor, and he's the reason that Fleetwood Mac became what we became..

Question: Why did he stop playing?
Self-contained rewrite: Why did Peter Green stop playing?