A couple looks out over Taughannock Falls where Krista Johnston and her late husband, Sgt. James Johnston, used to meet for lunch in Trumansburg, N.Y., . The two were high school sweethearts. She liked his easy smile, his jokes, his courtly Southern manner; he first called her Miss Krista and opened doors for her. Soon, they were inseparable, two outdoorsy types, zipping around the woods, splashing in the mud in a four-wheeler, hunting deer