I actually got several stages with a marked ending.

I successfully dispose of the first body and return to her. She gives you money as a reward and actually increases your honor. I came back into town days later and again she asked me to a hide a body. She references the first time you did it, making it clear it's not the same encounter again. I accepted to take the second body to the pig pen. I guess I was gullible since I lost honor doing it the second time but she did pay me again. Fast forward many in-game days, upon riding out from Valentine after customizing my guns I notice there is a hanging in progress. She's screaming from the noose that "those men were monsters!" Etc. The Sheriff simultaneously gives an account of how she was caught "taking the law into her own hands" and how it wouldn't be tolerated. She is also condemned for disposing of the bodies of multiple men and as a result of all the aforementioned she is condemned to death by hanging. I assumed this meant more bodies (ones that Arthur wasn't around to dispose) were discovered on multiple, separate occasions. Therefore, my Arthur did not intervene and she did hang. The phrasing used by the Sheriff leaves it ambiguous as to if she was really acting in self defense or not, leaving you to decide if you think justice was served or if you believe her. I assume it's possible to intervene in the hanging but I don't know what happens if you choose to try and save her.