Mr. March by Nicole S. Goodin

Luke Kingsford.
Ex-army soldier.
All round nice guy.
… And in love with his best friend’s wife.
Mia Vander.
Heartbroken widow.
Single mother.
… And surviving day by day.
Two years after Troy passed away before his eyes, Luke finds himself in love with the very woman he’s vowed to protect.
Luke wants Mia, even though he knows he has no right.
Mia feels things for Luke she never saw coming, but she’s overcome with guilt at the idea of betraying her late husband.
Luke wants to keep Mia forever.
Mia is scared to feel again.
Can Mia let go of the past and embrace a future with Luke? Or will Luke fail to keep his promise of never leaving her?