On the flip side of this as well, I remember when I was with Lou she had a dog. And I hated that dog for the four years I was with her, because it was her and her ex's dog.
On our first Christmas together I wasn't able to come and see her because the trains were down due to snow. So we agrred to spend it apart.
She spent her Christmas walking the dog with her ex boyfriend. Not cool.
The next time I did see her and the dog the dog ran up to the front door, saw me and sniffed me then walked off, and she said "I know mate, he's not your daddy is he."
I still remember that throw away comment, from four years ago. And it always upset me and really impacted on our relationship, I never got over it.
She would get constant texts and phone calls from her ex asking about that f**king dog. I have promised myself that if I ever see him I will break his face, because he ruined my relationship. Along with her shit attitude about it.
So it isn't all fun and games, having baggage from a relationship. I am sure she does feel the same way, and I am sure that when she spends time with the dog a piece of her is reminded of you.
It's shit mate. I feel for you.