Holmes great but unrequited love was Irene Adler (scandal in Bohemia)
With the exception of Irene Adler (whom he admired mostly because she outfoxed him) and his violin, Holmes lived entirely in his head. When he lacked mental challenges, he resorted to cocaine for stimulation. He is one of the least sensual characters in fiction. To ascribe any sexuality, hetero or otherwise, would be entirely inconsistent with his character.