True Devotion by Dee Henderson

True Devotion (Uncommon Heroes, Book 1) - Nick "Eagle" Jacobs' widow, Kelly Jacobs, is in the ocean holding on to dear life. She is holding onto Ryan, 15, but they were in a riptide that Kelly can not fight.  Waiting for rescue is her only hope.  Knowing that Lieutenant Joe "Bear" Baker is looking for her is her only hope.  Joe, was Kelly's husband, Nick's boss and best friend. Joe leads SEAL Team Nine and feels guilty about Nick's death, so he is reluctant to act on his feelings for Kelly.  Nick was killed on a mission to recover weapons being secreted out of Russia.  The head of the criminal group, Raider, retired after that mission; however, now he is being forced to facilitate another exchange.  Joe's team is eager to stop them.