Murder Mysteries, near as I can tell, are supposed to be about solving murders and not love stories. So anything that happens that is not directly involved with discovering clues and solving the mystery is generally frowned upon.
That aside, characters are what readers relate to more than plots. If you don’t have interesting characters, nobody is going to give a hoot about the story. So my characters – Dancia and Joshua will get involved with each other. It won’t be a big mating dance and it won’t be graphic, it will be “nice” and take one or both by surprise. Just enough to make it interesting and to allow the reader to relate to them.