This one's a bit more open to interpretation. While there are no canon romantic subplots in Sherlock there's a ton of subtext, most notably between Sherlock Holmes (Benedict Cumberbatch) and Irene Adler (Lara Pulver) and Sherlock and John Watson (Martin Freeman).
First, as regards Sherlock and Irene: I see their relationship as one more between kindred spirits than potential lovers. Plus Adler says in A Scandal in Belgravia that she's gay. But then she's into Sherlock emotionally (romantically? sexually?). And as for Sherlock and John… the subtext is there, and the show has fun with joking about how a pair of co-dependent male roommates resemble a gay couple. But canonically speaking, they're not lovers. If it turns out all the joking and subtext was a romantic subplot all along and something does end up happening in a later season I will gladly come back here and strike this entry out.
In a way, the relationships between Sherlock characters are too complex to mesh with the standard TV romantic tropes. Molly Hooper (Louise Brealey) loves Sherlock from afar, but there's never any question that nothing romantic will come of that. Watson has dating troubles, but his romances are less a subplot than a plot device, there to establish something about his relationship with Sherlock.
Basically, Sherlock is not your standard show, and it's not going to play into the standard "will they or won't they/pining from across a crowded room" romance tropes that other series do. Don't get me wrong. I don't fault other series for doing that. It’s fine. But while there’s at least a good assortment of movies with no romance Sherlock is literally the only adult TV series I can think of that qualifies. (TV shows normally show a larger swath of life than movies, after all, and real life generally does include romance.) So I’m including it. Your mileage may vary.