Her loyalty to him, although admirable, was sorely misplaced
The same drama has probably happened ten thousand times in human history. If Palin hadn't been loyal, I and many others would have lost some regard for her as Palin surely would have lost regard for herself. Pretty hard to live with oneself knowing one had betrayed loyalty and honor for self-advancement.
Yet knowing that being loyal could end up with harmful, disastrous consequences, a gamble on politics (McCain might not have been re-elected) and risking the wrath of critics.
I don't know what I'd have done in her shoes.
But I can imagine she might be breathing a sad sigh of thanks that McCain isn't going to back her.