Eh, I knew the intent of the Tara Dawn interactions, I guess I just forgot to mention that in my hurried writing. My comment was meant to say that it felt more suddenly overly intimate. I don't remember too many scenes where a point was made to show Tara as a mother to Dawn before those ones, though I'm sure they were there.
Dawn was basically being looked after by Tara and Willow (which lets be honest, was probably more Tara than Willow) while Buffy was dead. So basically that development happened between seasons. There are some little things but Tara is Tara (with all her family issues) so she backed off more when Buffy returned. Whenever Tara and Dawn interact without Buffy around you can see it more.
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"Hope is allowed to be stupid, unwise, and naive." ~Sir Chris