Forty years after their all-time breakup album Rumours, the mythology and romance — literal and otherwise — of Fleetwood Mac still towers over the band's imposing legacy. You cannot discuss Lindsey Buckingham and Christine McVie's new duets album, and the tour that brings them to Ruth Eckerd Hall Thursday, without breaking it down through the lens of the band that made them pop songwriting icons.And, it turns out, neither can they."Obviously, there's been so much written about Stevie's and my relationship, and the underpinnings of the romance that go along with that and create that part of the musical soap opera that was Fleetwood Mac," said Buckingham, 68. "Unlike with Stevie — with whom I did have a romantic relationship, and with whom we had a great vocal blend — Christine and I had the kind of bonding that comes from both of us being grounded in our craft as musicians.""It's a strange one, really, because we're not really the best of chums," McVie, 74, said in a separate call a little later. "We don't really hang out very much together. But we have a really strong musical bond with each other. Once we're in the studio, we work as a team really well. We inspire ideas with each other. It is quite amazing, really, that I can listen to something he's playing and tooling around on, and then we link up off each other very well. It's been like that over the years — we come up with different ideas, and cooperate in a very natural way."Buckingham and McVie perform together at 7:30 p.m. Thursday at Ruth Eckerd Hall. Tickets are $63.25 and up. Click here for details.For more of our interview with Buckingham and McVie, click here.