from my understanding, in TX (if that's where they reside), engagement rings are a conditional gift and completed once married. If Oscan broke it off, and for iffy reasons, his ex fiance may get to keep it. If she broke it off, it must be returned as the conditions for the gift weren't met. Similar thing happened to R Williams (WR) not too long ago where is fiance broke it off, she tried to keep the ring but the court ordered it returned. Soooo, it depends on WHO broke it off and if Oscan did, that he had very good reason (i.e. affair, etc.).
In NY, where I'm from, it's a conditional gift until marriage regardless of who or why in the event a marriage doesn't happen.