The bond Chris and Stacia have is based on the fact Stacia was exposed to a little of Chris’s blood when she was turned. It’s never been a ‘mate’ bond.
And I suggest you read a few more authors who write about shapeshifters. It isn’t an uncommon idea that the person’s animal shape is actually a sentient being in its own right, hence the ability for Stacia’s wolf to recognize their mate is Declan before Stacia.
And, if we’re talking creepy… it’s the whole white knight thing Stacia had going for Chris, especially once she knew how deep his relationship with Tanya is. Only a fool stays stuck on a person who is unavailable. And, even if it was only Stacia’s subconscience that moved on to Declan, she was smart enough to move on.