the same thing happened to me with my runners. I had one that was really attached but once she realized the big girl pool was available all the time I was old news.Last year I transitioned my 2 bonded ducklings outside with no issues when they were 2 months old. Once they saw their new pool in their own space, they forgot all about me
Good luck! Like @Miss Lydia said, it’s probably harder on the humans than the ducks.
