A better ending would have been...
If Dan had saved her and become her new Connie. She's still stuck in the house and crazy, but this ending would have been dark, sad, and poignant all at the same time.
shareAgreed.
The whole "and now I'm cured" ending just didn't sit right with me. You don't have a severe, debilitating, years-long phobia/mental health issue and then just get over it.
They would have had to write the character of Dan differently to make your ending work, because as written I don't believe he would have stayed with her (despite feeling guilty about what she went through).
Ultimately I felt like the final act was a mess, and especially the explanation for why she was house-bound. From the sound of things, it was her brother who sucked her into the ritualized murders--but because they are holding onto that as a twist we get very little of the brother character.