I Don't think they forget to easily either. I had a pomeranian named Roxie who was about 5 months old, she just wouldn't get along with Oreo (she was a whopping 6 pounds compared to Oreo) So I gave her to my Uncle and his family, since they'd been looking for a dog like crazy, but couldn't afford those high priced ones.
well it had been a few months since i've seen Roxie.. i'd always just hear how she was doing and stuff like that. I even bought her a shirt from BarkinDog lol.. My uncle and his family live in my old house. My parents go there quite often to fix up the place... and Roxie would always growl and bark at them, so weird because back at our house, Roxie would always whine and whimper when she wanted attention from them.
When Roxie saw me it was like she never forgot who i was, what i smelled like, she just pounced on me and gave me so many kisses i had a wet face!.. i don't think dogs forget you..
maybe your doggie just knew the tension between you and the ex.
just a thought.. (a long one at that
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