Irene Adler is the only woman mentioned in the original book who is related to Sherlock Holmes, but she is married. She gave Holmes a new understanding of women's intelligence. However, the China student in the novel explained that this does not mean that Holmes has feelings similar to love for her. Many people think they are related, which I think is incorrect. At best, they just appreciate each other.
In the original work, Holmes himself said, "Love is a sentimental thing, which contradicts what I think is the most important thing. I will never get married, lest it affect my judgment. (symbol of four)
To sum up, Holmes thinks that love is not a necessity, and not everyone needs it.