Legal Question in Family Law in Oregon

First, you are lucky she gave the ring back. In some states, she would not have to do so.

Second, did you have a clear understanding and agreement with her, when you gave her the ring, that in the event she breaks off the engagement and returns the ring to you, and you then incur a financial loss in reselling the ring, that she would bear the liability (in whole or in part) for the resulting loss? In the absence of such an agreement, the loss (financially and emotionally) is entirely yours.] And such is the law here in Oregon.