ABBA star Björn Ulvaeus is separating from his wife, Lena Ulvaeus, after 41 years of marriage. “After many wonderful and eventful years, we have decided to go our separate ways,” the pair announced on Wednesday via the musician’s spokesperson. According to the statement, they want to remain close friends and continue to celebrate their grandchildren’s birthdays and other family events together. Björn Ulvaeus is one of the four members of the legendary Swedish pop group ABBA, which produced hits like “Mamma Mia” and “Dancing Queen.” At the height of the ABBA era in the 1970s, he was married to …