http://www.buckinghamnicks.info/interview-davidforest
Apparently, under a pseudonym, Fritz released a single in 1968:
https://www.discogs.com/Sincerely-Sa...lease/10001338. Here's the B-side, with Lindsey on lead vocal and Stevie on backing vocal:
https://www.youtube.com/watch?v=YrEX9fHqcVQ
It sounds as though Lindsey and Stevie dated casually toward the end of Fritz in 1970, and then seriously after the band's breakup in 1971: "They began while Fritz was together but didn’t get really ‘heavy’ until after the breakup." How a couple can stay together for five years without getting married baffles me. I wonder whether Lindsey ever proposed. I wonder whether Stevie got pregnant and Lindsey wanted to keep the baby and get married, but she chose to do neither.
In the end, their manager came to view Buckingham Nicks as too mellow (the album is somewhat folky, which frankly is very much to my taste): "They were meant to be rock and rollers. Buckingham Nicks was just not hard enough. The public loved them as rock stars with Fleetwood Mac." "Stevie and Lindsey on their own were so much better than Fritz, and, of course, Stevie and Lindsey as part of Fleetwood Mac was the BOMB."