My opinion is not worth much in this subject, but I think Mr. Shadow might be doing the right thing here. If she demonstrated to be truly sorry, she will be shocked when she is purposed. She won’t be expecting it, and will probably feel she does not deserve the complete forgiveness he is giving to her. It is a perfect demonstration of how much he loves her.
But, then, he is risking a lot because she might not be truly sorry, which makes it a very strong proof of love. And also a proof that he and his girlfriend are having a relationship rather than a power struggle.
What I think is Shadow should do it, but only if he is really, really, really sure about it. Be careful.