Pauline McDaid, who hails from Derry, told Northern Ireland's Sunday Life how much she enjoyed the Friends actress' company during her holiday in the Emerald Isle for Johnny's 38th birthday.
"We all love her," said Pauline, who added that Courteney "felt at home" during her stay.
Courteney has grown close to her future mother-in-law Pauline
"John is very much a Derryman," added Pauline. "So to be able to show Courteney around where he grew up and around his history, he was as proud as punch."
Courteney Cox scouting wedding venues in Northern Ireland
As well as being given a tour of the locations close to Johnny's heart, Courteney also got to know his family and friends.
Courteney and Johnny are said to be planning on marrying in Ireland
The Snow Patrol musician was not able to meet his fiancée and her 10-year-old daughter Coco upon their arrival, meaning that his sister Aine was charged with the responsibility.
Ed Sheeran confirms Courteney Cox is living with his pal Johnny McDaid
"John was actually with me in Liverpool attending my younger son's graduation," explained Pauline. "So Aine, my oldest daughter, brought Courteney on ahead and took her down to Shrove, which is her favourite beach in Donegal."
Courteney and Johnny were introduced by their mutual friend Ed Sheeran
Retired art teacher Pauline added that Alabama-born Courteney fitted right in to the Derry lifestyle.
"She wanted to do normal things like go up the town and do her shopping," she said. "She even picked up some Derry phrases when she was here. And with her being an actress, she can do the best Derry accent."
Courtney's daughter Coco, whom Pauline described as a "wee pet", also enjoyed her trip to Ireland.
"We were all out playing hide-and-go-seek when the weather was so beautiful and she just loved it," said Pauline. "She loves photo bombing any photographs, if you look closely, Coco's there somewhere!"