Wasn't Maggie wearing some strange cheap plastic ring when she was in the hospital?
Barnabas has softened towards Maggie, giving her a second chance. She's not interested. Would she be more interested if she knew that she now has a rival for Barnabas's affections? No, probably not. She's true to Joe.
As I watched her despairing, I thought about being locked in that room, knowing that my only way out was death. And for me, that's final: I do not believe in life after death. But Maggie's world is different. She has learned that the supernatural does exist. If Barnabas murders her - not to make her a vampire, just to make her dead - that won't necessarily be final. In her position, despite the awfulness, I think part of my mind would be saying, "Sort of unexpected...what are the implications?" And I'd have to laugh at myself for being so utterly wrong. But Maggie probably has believed in life after death all along, so the existence of vampires does not change her view of the universe.