Kimberly Buffington-Quaid initially filed for divorce in March (12), citing "discord or conflict of personalities" for the breakdown of their union, but she withdrew the papers in May (12).
The couple, which recently moved to California from Texas, tried to patch up its differences and celebrated its eight-year anniversary in Bora Bora in July (12), but the relationship appears to have crumbled once again.
Buffington-Quaid is now seeking joint legal and sole physical custody of its four-year-old twins, in addition to spousal support and the cost of her legal fees, according to TMZ.com.
A statement issued by the actor's representative reads: "Kimberly and Dennis Quaid have decided to legally separate after eight years of marriage. They ask that their privacy and the privacy of their family be respected during this difficult time."
Buffington-Quaid reportedly filed for legal separation instead of a full divorce due to state restrictions in California, which requires divorce petitioners to have lived there for a minimum of six months before they can move to officially end their marriage.
It's the Traffic star's third failed union - the 58 year old was previously married to actresses Meg Ryan and P.J. Soles.