WHY DO PEOPLE KEEP THINKING THAT SHERLOCK/IRENE IS A THING?
Like not just with BBC's Sherlock but it's actually canon in ABC's Elementary. There wasn't any form of romance in the relationship between Sherlock Holmes and Irene Adler in the original books by Arthur Conan Doyle. The only slightly special thing about their relationship in the ACD universe is the fact that she beat him, what makes her the only woman who ever beat him. That's it.
I actually really like that Sherlock was beaten by Irene but BBC couldn't even stick to that part of the books. (I hate that BBC's Sherlock beats her in the end because she fell in love with him. Ugh. She's a great, strong character in the books just like she is in the beginning of A Scandal In Belgravia.)