Here with Me - The Archer Brothers, #1

Ryley Clarke has grown up with the military in her blood, with both parents serving their country. Ryley knows the risks of being married to the military. But when the unthinkable happens, and her future husband is killed in action, Ryley can barely survive... until Evan's twin brother, Nate, helps her pick up the pieces. After serving on a special mission with the military for six years, Evan Archer returns home to find the unthinkable - the love of his life, Ryley Clarke - engaged to his brother, Nate.  With Nate on deployment, Evan needs to figure out what happened in his absence, and more importantly, how to win Ryley back from the man he once considered his best friend, but now thinks of as his rival.
Their story continues in CHOOSE ME