It's About Time — Anne Barbour

Widow Austen Wiley, unable to spend as much time with her four-year old son, David, as she wanted to, drives from her home in Kansas to a summer job in Nebraska's panhandle near Chimney Rock. When she arrives, she learns that Mark Thomas, the owner of TrailWays, which provides historical treks on the Oregon Trail, was expecting a man. Perhaps because he and David established an instant bond, he decides to let her stay.There was constant strife between the two, but also an immediate attraction, obvious to everyone. They tried to ignore it because of past experiences, and continued to address each other as Mrs. Wiley and Mr. Thomas, but there were instances when they couldn't avoid their attraction and it came close to becoming something so much more than almost kisses.