Fray

verb

1. To (cause to) unravel; used particularly for the edge of something made of cloth, or the end of a rope.

   "The ribbon frayed at the cut end."

2. To cause exhaustion, wear out (a person's mental strength).

   "The hectic day ended in frayed nerves. (Metaphorical use; nerves are visualised as strings)"

3. Frighten; alarm
4. To bear the expense of; to defray.
5. To rub.