I have made and continue to make decisions that my parents do not agree with. I do accept the responsibility for those decisions, and many times I have to pay the price.
They way I look at it:
I have not told them how to live their life, they have lived their lives on their own terms, and so must I.
I can see the same flags you do, but, it is her life, her choice.
All you can do is let go and pray.