Even though it's so blatantly obvious to the reader, I think Rachel basically does her very best not to think about it, because if she considered how much Ivy is actually IN love with her, it would make her ~uncomfortable~. She tries whenever possible to make it about the vampire attraction Ivy has towards her, rather than the fact that somebody does actually love everything about her, despite all her faults.

Maybe we'll eventually get a ~realisation~ scene out of her at one point. Most likely when Kim decides it'll be fun to bring the sexual tension back to full force once the books are wrapping up and all the men are officially boring the readers to death.