Carey's subsequent musical releases followed the trend that began with "Daydream". Her music began relying less on pop and adult contemporary-tinged balladry and instead incorporating heavy elements of hip-hop and R&B. On "Butterfly", Carey collaborated with a bevy of producers other than Afanasieff, such as Sean Combs, Q-Tip, Missy Elliott and Jean Claude Oliver and Samuel Barnes from Trackmasters. In mid-1997, after four years of marriage, Carey and Mottola separated. Carey described Mottola as increasingly controlling, and viewed her newfound independence as a new lease on life. In the booklet of her twelfth studio album, "Memoirs of an Imperfect Angel" (2009), Carey wrote that she considers "Butterfly" her "magnum opus" and a turning point in both her life and career. "Butterfly" introduced a more subdued style of singing, with critics noting Carey's incorporation of breathy vocals. Some viewed her lack of propensity to use her upper range as a sign of maturity, while others questioned whether it forebode waning vocal prowess. The music video for the album's lead single, "Honey", her first since separating from Mottola, introduced a more overtly sexual image. "Butterfly" became Carey's best-reviewed album, with attention placed on the album's exploration of more mature lyrical themes. In their review of the album, "Rolling Stone" wrote "not as if Carey has totally dispensed with her old saccharine, Houston-style balladry [... but the predominant mood of 'Butterfly' is one of coolly erotic reverie." AllMusic editor Stephen Thomas Erlewine described Carey's vocals as "sultrier and more controlled than ever," and felt the album "illustrates that Carey continues to improve and refine her music, which makes her a rarity among her '90s peers.'" Though a commercial success, the album failed to reach the commercial heights of her previous albums, "Music Box" and "Daydream".