This achievement is missable. You cannot get this achievement until after you have convinced Nericon to let you cross Mardanues Plaza, see the Oaken Resolve achievement for more information.
In Crow’s Nest you will see a burning house, create a save and then approach it. Claire will then talk to you and ask you to get three things for her from her house. The three things are her engagement ring, her baby, and her love letters. The love letters are on a desk on the ground floor in the inner room with the bed. Once you have retrieved them, run up the stairs and get the baby from the cradle from the second room. Then turn around, run back to the room with the stairs and get the key from behind the fallen bookcase and use it to open the small box with the engagement ring in the same room the baby was in. There is no need to worry you have more than enough time to get each item and come out of the house alive. After you have got all three items leave the house and speak to Claire and the achievement will unlock.