If lady slayer MATT LAUER is cheating again, pals fear it could trigger a heartbreaking anorexia relapse for his long-suffering wife, Annette Roque!

Last week, The National ENQUIRER showed the skirt-chasing “Today” show host on his boat with a mystery blonde in the Hamptons, off the coast of Long Island, N.Y.

While Matt’s rep insisted the woman was a family friend, an eyewitness told us the couple acted suspicious: The “smoking hot blonde” ducked and tried to cover her face when the pair spotted a photographer taking pictures.

Now, a friend of Matt’s Dutch-born model/wife is worried a possible cheating scandal could devastate her.

In 2007, Annette lost weight rapidly, and her retired stepfather, Dr. Dick Struijk, told The ENQUIRER that Annette was suffering from anorexia, and he confided that “there had been troubles in the marriage.”

Annette, 48, has been married to Matt, 56, since 1998, and has endured several cheating scandals. At one point, she filed for divorce but the pair reconciled.

Fearing for Annette’s health, her friend recently declared, “Matt ought to stop horsing around on his boat and appreciate Annette more.”