As the narrator of the story, we only know what Constance tells us, and Constance is not given to sentimental digression regarding her own feelings or speculative descriptions of the feelings of others. She makes us work for our information and forces us to read between the lines to form our own opinions. For example, when she tells us about the Singer man depositing her at Mrs. Florence's Country Home for Friendless and Erring Women, she does not tell us if she felt abandoned and unloved, whether she wept, pleaded with him or lashed out in anger. She just relates the facts. We have to infer that she did not blame him from the fact that Fleurette's middle name, Eugenie, is for the Singer man's first name, Eugene.
She is almost as secretive about her feelings for the sheriff. But we're too good for her; we put together the little hints given in a casual mention of the warmth of his hand in hers, the look of the sun on his face, his little half smile, and, when she and her sisters are tending to his gunshot wound, that description of the freckles on his shoulder. There's a tenderness in her voice that Constance can't hide from us. Even Fleurette notices what a good time Constance had when she "got to run around with Sheriff Heath."
Knowing what Sheriff Heath feels about Constance is a bit trickier as his thoughts are filtered through her voice. We do know he admires her intelligence from that look he gives her when she comes up with a solution to the problem of Ewing, his amusement when she strong arms Kaufman into submitting his signature for the handwriting analysis, and his praise for her good investigative work in locating Bobby and ascertaining Kaufman's involvement. But admiration is not a romantic feeling.
His actions show that he cares about the welfare of the Kopp sisters as he goes against his superiors and puts in a lot of extra hours to provide protection. But that could be just another example of his integrity as a public servant.
And he does seem to give preferential treatment to Constance, confiding in her the details of the case on their frequent walks, enlisting her help, even entrusting her with a gun and teaching her how to handle it before he does the same with her sisters. Add to that the fact that we never see any tenderness between the sheriff and Mrs. Heath and . But the sheriff remains ever the married man and when he offers Constance a job as his assistant, she is still "Miss Kopp"
But who can blame us for seeing what we want to see. After all, even flighty Fleurette assumes that there is a mutual attraction between the sheriff and her sister. When Francis tells her his fear that one of the sisters would shoot Kaufman and land them all in jail, Fleurette responds, "Sheriff Heath would never put Constance in jail. He likes her too much." The hints are all there, but we're a long way from having proof. Guess we'll all just have to wait for the next installment to see if we were right.