Wesley Ward feels Acapulco will enjoy "the best of both worlds" by being trained by Aidan O'Brien as well as mating with Galileo.
Winner of the Queen Mary Stakes at Royal Ascot in 2015, her three-year-old season was interrupted by injury and she missed the chance to run in England last summer.
But as she already had a date with Galileo lined up, Ward suggested the switch to O'Brien would be best for all parties, with a tilt at the King's Stand at Royal Ascot the chief goal.
"Coolmore have been brilliant to me, they really have, and while I'm sad to lose her, it's for the best" - Wesley Ward
"I really thought she'd win at Royal Ascot again last year as everything had gone so smoothly with her," said the American handler.
"She won her prep race and then stepped up to win a stakes race really easy and I was so confident.
"Then, when we get her over there she had an abscess on her foot and we spent the rest of the year trying to build it back up.
"With everyone from Coolmore being at the Breeders' Cup we tried to get her ready for a race that weekend but it was a bit of a rush. She ran well but was just a few breezes short.
"She was perfectly sound afterwards, though, and that's what pleased us so much. I said afterwards there was still plenty she could achieve.
"Obviously, when you have a date with Galileo you don't want to miss it but we all talked and by having Aidan train her she gets the both of both worlds as there's no better trainer.
"It would be a lot to ask of her to go and see Galileo and then come back and race for me so it's best she stays in Ireland.
"Coolmore have been brilliant to me, they really have, and while I'm sad to lose her, it's for the best.
"I had a chat with Aidan about her at the Breeders' Cup and I'm looking forward to seeing what she can do."