Nicollette Sheridan and Michael Bolton are again going their separate ways, a rep for the actress tells PEOPLE exclusively.

"Nicollette Sheridan and Michael Bolton have amicably ended their engagement," said Nicole Perna. "They appreciate your respect for their privacy in this matter."

The couple's relationship originally started in 1993, and lasted about a year and a half.

The musician, now 55, and the Desperate Housewives star, 44, then resumed seeing one another in 2005 - and in March 2006 had announced their wedding engagement.