Junna fell for Hane/Floria Rose the moment she woke up after being healed by her, despite knowing her for quite a while before that, so the corruption must've prevented it. Was the corruption broken by Hane's healing?
I want to think it was both her heart and brain that were corrupted, and by striking her down and then reforming her heart it recovered and let her love again, love someone Junna would've fallen for ages before if not for the corruption. But a part of it remains in her head, which would explain her yandere-ness and memory issues.
Sidenote, the shithead seems to have shed actual blood judging by the splatters at the end there, as opposed to the petals and leaves we've seen so far, which seems to be a magical girl thing (sane or corrupted).