He knew that there was no one that could treat her with such kindness and concern in the same way that Zach did and for that she was beyond grateful.
She didn't know how she had ended up being around him but she knew that she was grateful for it and her admiration for him and her appreciation only seemed to grow a tenfold.
He valued her not just as someone that he could acquire serviced form but as a human being someone thar had feelings and was to be concerned about,.
He didn't have to tell her that he cared for her because he made sure that he showed it to her regularly. That was something that she hadn't been able to experience before and she was pleasantly surprised by how he was willing to keep to his word.
He was the first man that was kind to her not because there was something that he wished to gain from her but simply because of the fact that he wanted to be nice to her and he saw a need to spread his kindness and help her out.