Marion Zimmer Bradley's Darkover. Darkover Anthology, #11

...an incredible blending of fantasy and science fiction. Eventually the Terrans rediscover their long-lost -- and now alien -- colony: Darkover. Things are different there. While adolescent male homosexuality is generally tolerated on Darkover, men are expected to outgrow it. When Dyan Ardais takes lovers young enough to be his sons, he risks not just his reputation, but his life. Life in a Tower as a Keeper, the chaste virgin who holds a circle together, is grueling.
Few succeed in the long, painful years of training. The ones who do have power greater than any queen, but what happens to the ones who don't?Darkovan technology is based on matrix stones that amplify psychic gifts, and people with those gifts work in the Tower circles. But duty to family outweighs everything else, and anyone can be called home from the Tower to marry as her family dictates. A Comyn lady can have lands, wealth, family...everything but freedom.
Women can become Free Amazons, but that life has its own set of challenges. Before a candidate's trial period ends, she must decide if she is truly meant to cope with everything being a Free Amazon entails.