I sold a maltese that had many issues and i worked very hard with her?

and the friend who took her in treats her WELL . they are single no kids and the pup is now 9 months old. i got her at 5 months old , she was antisocilized to make story short i did ALOT OF WORK ON HER she was even attacking vets and groomers. unusual for a maltese with this temperament, anyways she has been in my friends home for 3 months now. i went to visit for the 1st time last night, he told me she screamed and cried when i left and wouldn't sleep all night she cried. now i don't understand just why they say dogs live in the Moment for some reason this dog is very attached to me . i feel bad for my friend now . he said its ok but he was in a AWE to when she reacted this way when i left to. any one have any intakes on this ? is it because i done so much training and work on her ? Or is it she wants to come back home with me? my friend said he don't have a bond with her as he should , he said she is alot of work and training . which i forewarned him prior to this, its not that he don't like her he just says he don't have a huge bond with her yet , i find this strange since many do with their pets certainly with in 3 months. as i mentioned i donno who says dogs live in the moment because she certainly didn't forget me at all i left a footprint on her heart as she left one on mine.