He was the last of the Valois line. He became king illegally (according to some sources). He produced no children. He had "minions," a group of very close friends he pampered and showered with favors: some say they were more than just friends. He has been described as effeminate by historians and novelists alike. He had an aversion to women. He never entered his wife's bedroom. In his trilogy in which Henri figures as one of the major characters, Alexandre Dumas, Pere all but refers to him as homosexual.
Now suddenly historians reverse their opinion on him. According to them he had a stormy affair in Poland with a woman he loved. He also loved his wife with whom he had sexual intercourse practically every night. The canard about him being gay was concocted by his slanderers.
Why the sudden change?
Addendum (light-hearted: pay no heed): Upon popular demand, I removed the word "gay" from the title, since "there were no gays prior to the 20th Century." There were also no homosexuals prior to 1880, and no Sodomites prior to the advent of Christianity except among the Jews; and no Sodomites anywhere before Sodom. Maybe they were referred to, or referred to themselves, as "individuals of non-traditional sexual orientation" in ancient Egypt, I don't know. The question is not about such individuals as a group; it's about Henri III of the house of Valois, no more and no less.