At some point prior to 1898, Allison married Terrence O'Dowd. However, she grew to hate her husband due to the way he treated her, and later fell in love with an outlaw named Cliff. She eventually ran away from her husband to live with Cliff.
Events of Red Dead Online
During the mission "Love and Honor", Terrence asks the protagonists to rescue Allison, claiming she was kidnapped by outlaws and taken to Twin Rocks. Once the protagonists have dealt with Cliff's gang and enter the building that Allison and Cliff are in, the couple plead with the protagonists to leave them be or save them. The players are then given the choice of either helping Allison and Cliff escape, or killing Cliff and bringing Allison back to Terrence.
If the players choose to help Allison and Cliff, they will escort them to Mercer Station while fending off gunmen hired by Terrence. Afterwards, the couple leave to start a new life elsewhere, far away from Terrence.
If the players choose to kill Cliff, they will kidnap Allison and take her back to Terrence while fending off the remaining members of Cliff's gang.
As shown in the few interactions with her, she holds passionate hate for her husband, Terrence O'Dowd, and would much rather be with her lover Cliff. When the players first encounter Allison she is obviously in distress and pleads with the players that she will "not go back" to Terrence.
Red Dead Online