The Shadow Matrix (Darkover) by Marion Zimmer Bradley

After spending her youth in the Terran Empire, Margaret Alton returns to Darkover, the planet of her birth. There she discovers she has the Alton Gift--forced rapport and compulsion--one of the strongest and most dangerous of the inherited Laran gifts of the telepathic Comyn--the ruling families of Darkover. And even as she struggles to control her newfound powers, Margaret finds herself falling in love with the Regent to the royal Elhalyn Domain, a man she has been forbidden to marry, for their alliance would irrevocably alter the power balance of their planet!