When Marilyn McCoo and Billy Davis Jr. took the stage last month at the Tilles Center concert hall at Long Island University in Brookville, New York, the husband-and-wife performers sported matching colors with sequins, frequently put their arms around each other, and reminisced about their 50-plus years of performing together — both in the supergroup the 5th Dimension and as a vocal duo. The couple received much applause for their smooth renditions of 5th Dimension hits from the ‘60s “Up, Up, and Away” and “Wedding Bell Blues,” as well as for newer material from their 2021 album Blackbird.