I think it's great that you've rethought the ring thing and that you want to give it back to her. Here's the caveat, though....I (two cents) think that you have to time the "give back" perfectly and make sure (a thousand times) that you're not giving it back as a renewed sense of commitment from her BUT because it is hers.
IOW, I'd hate to see the babysteps of let get squashed because she thinks the ring return is some sort of sign from you of renewed hope -- ya know?
So, think about how you could do it right...my suggestion is make it seem somewhat like an afterthought, make sure it's at the end of an evening (as she's leaving) and make abundantly clear that you "realized that I had no right to demand this from you. this is yours to keep." Avoid words like "no matter what happens" and "commitment" and "promise" and "future". I'd STILL expect her to be put off a bit and it's key to reassure her that it's ONLY about returning something that is hers w/o engaging in an R talk.
Sage
Relax. Appreciate. Be calm. Laugh. Enjoy. Be secure. Be loving. Be loved. Don't personalize. Don't ASSume. Accept. Be grateful.