Her thinking HC loves BS or that BS might love her back has been there since the beginning so it's not really anything new to her. Just that situation made her think about it again. At the same time, she like to fight with BS and she gets happy when he appreciates her or does something for her. For someone like Appu, it will really take a lot more to give up both because of her own fighting nature and because of her yearning for love.
Personally, I went through exactly the same thing in the past 3-4 years but it was with my sister instead. At least here it's only a relationship of few months and words of few days. I tolerated such behavior for years now and only couldn't let go because it was my own only sister. It took something that literally changed my whole life and my entire family, even extended family's lives for me to completely let go now.
We have strange, different and ( at times) unexplainable reasons why we hold on to things and people even after they become toxic.
Sending tight virtual hugs to you. 🤗🤗❤️