This reads like two different loglines:
"When her best friend's fiance comes to town, a sheltered outback girl is faced with feelings she never though she would have..." The END
"When he (her best friend) asks her to ?write a ?song with him about the suspicious death of a local shearer, she discoverers that the culprit is someone close to home..." The END
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The problem is, I don't see any connection between the two halves of the logline.
In other words, why bring up a fiance' and her feelings, if they have nothing to do with the main plot, which is discovering who killed the local shearer.
I would just concentrate on the 'A' story (The suspicious death of the shearer) and leave the 'B' story (The fiance and feelings) out of the logline. (Keep it in your script but just concentrate on the 'A' story for the purposes of the logline)
You obviously have a story here. If you concentrate on the main story line, (for the purposes of the logline) it will read far stronger and be more likely to captivate your reader.