In April 2002, their third album "Sea of Love" was released while Joo was in New Jersey attending Rutgers University. As a result, Hwang began to perform by himself until Joo returned to Korea. The lead single from the album was the title track, a poppy ballad, and it became a summer hit. Their second single "Condition of my Heart" was written by American singer Brian McKnight; in contrast to the first single, "Condition" was a heavier ballad. The single signaled the duo's musical transition from bubblegum music to R&B. Along with their music, their image began to change as the duo traded in their "flower boy" look for a more masculine image. In the same year, the label released a female duo that was said by fans to complement Fly to the Sky known as Isak N Jiyeon, however the two groups never worked independently with each other.