Regal Rising by Viola Grace

Regis has spent her life knowing that she had a mate, and he was imprisoned. Sneaking into the Stronghold to find her mate was almost as difficult as leaving him there.

Regis grew up with a good family and supportive friends. Having an old soul in her system caused her to skip a lot of the experiences that were treasured by those around her, but she knew what she was after. Her husband and daughter were out there somewhere; she just had to find them.
Her sister, Rex, is at her side during her adventures, and with her nerves of steel, she faces down deadly guardians blocking the way. It is enough to get them into the Stronghold, and from there, Regis has to let her link to her past lead them from the past and into the present day.