I was wondering about something.

After Maria has eloped with Henry, Mary's advice is to play things down and hope that Henry and Maria get married.

Now my question: could it be that Henry's reputation could also be hurt by this episode?

In this case, Mary's reaction that ends up devastating Edmund, could be explainable. She could be desperately trying to save her brother. In this state of mind, and seen from this perspective, her motive was to plead for Edmund's assistance for Henry (not Maria). She might have been so caught up in her thoughts that when Edmund finds her statements so cold and repulsive to him, she only then realizes the further implications of what she has been suggesting.