Milo by Lily Morton

Once upon a time a brave knight rescued a young man. Unfortunately, he then spent the next few years bossing the young man around and treating him like a child.
Milo has been burying himself at Chi an Mor, hiding from the wreckage of his once promising career and running from a bad relationship that destroyed what little confidence he had. Niall, his big brother’s best friend, has been there for him that entire time. An arrogant and funny man, Niall couldn’t be any more different from the shy and occasionally stuttering Milo, which has never stopped Milo from crushing wildly on the man who saved him.
However, just as Milo makes the decision to move on from his hopeless crush, he and Niall are thrown into close contact, and for the first time ever Niall seems to be returning his interest. But it can never work. How can it when Milo always needs rescuing?
Content warning: There are descriptions of domestic abuse in this book.