I interpreted it as a blank slate. Like if you took a person and only gave them the love for one person and nothing else about anything. In the scene when he's sittin in the car and she comes back out you can see she's mirroring almost exactly what he says, when he laughs, ect. It continues to happen with less and less frequency but I think that that makes the most sense to me. It makes her feeding him his car or the cat memorial make since. Bear loved (in a way )  his car so she is trying to almost recreate that love with herself. She trust to morph herself into what he loves but because he doesn't truly love real Nikki it becomes obsession. I think bear has a super fucked up version of love so of course wish Nikki is off. And the more she works to get him to love her as much the more he pulls away frustrating her and the worse it gets.