I try not to but you can't help it. Why did I not see, what could I have done different?
I can't escape those questions in my mind yet.
I don't know if you've ever seen this movie or not, 'What Dreams May Come'. A lot of people hate it.

I was moved by it (theatrical ending. I would have hated the intended ending; the same people who hate the film, love the intended ending for being very bold;so YMMV), especially the scenes in hell.
He loved her, even when she could no longer love herself or see his love for her. It was all he could do, or could be asked to do. The rest was up to her.
There's nothing you could have done differently. You loved as best you could. It was up to her at that point. If she wasn't going to take your hand and your love offered to help pull her out, with all the love you gave, then she wasn't going to do so if you offered a little more.
It is possible, if she was on certain medication, that the medication could screw up her thinking processes; but that's for a physician to determine, and that's still not on you.
You loved her, and that counts for something. That counts for everything.