Ellen Wexler in Smithsonian:
On her 25th birthday in February 1947, Felicia Montealegre sent a giddy letter to her new fiancé. “Lenny, my darling, my darling!” she wrote. “I am a quarter of a century old, a very frightening fact!” Recent developments, she went on, included the arrival of a black cocker spaniel puppy (“She’s mine, my very own!”) and an impending driver’s license exam (“I drive alone all over the place, up hill and down dale, heavy traffic and all—and I’m great! So there!!”).
Felicia, an actress, had been engaged to Leonard Bernstein, the 28-year-old wunderkind composer and conductor, for two months. She was, like most everyone in the man’s orbit, perilously in love with him. Still, beneath the bubbly, starry-eyed adoration, she felt something was amiss. “What’s with you?” she wrote. “You never really tell me how you feel—is it that difficult?” Come fall, the engagement was off. Then, after a four-year interlude, it was back on. A wedding quickly followed.
Yet the biggest obstacle remained: Bernstein, a closeted bisexual man, had always conducted numerous affairs with both men and women. In 1947, the secrecy had been evidently too heavy for the relationship to bear.
More here.