Hmm, the vast majority of historical romances I've seen have prominent love triangles, but maybe some of these will work for you:
- Splash Splash LOVE*
- Sungkyunkwan Scandal - the SML never confesses his feelings
- 100 Days My Prince - the romantic dynamic is somewhat similar to Love in the Moonlight; the FL is never torn and the SML is generally respectful / helpful
- Legend of Fu Yao - the SML gets his own love story later in the drama
- The Princess' Man - there is a love triangle dynamic in the beginning, but as far as I can remember it's not relevant later on in the story
- The Eternal Love*, season 1 - the FL is from modern times, but her soul travels back in time and enters the body of Lady Qu; Lady Qu Tan Er was the childhood sweetheart of the ML's rival Mo Yi Huai; in reality there isn't a love triangle because the ML and FL love each other and Qu Tan Er and Mo Yi Huai love / loved each other, but because the FL and Qu Tan Er share a body things get a bit complicated
- Live Up to Your Name* - there's a SML who likes the FL, but he never explicitly confesses and he has very little screen time
- My Only Love Song* - the villain is obsessed with the FL but it's not much of a distraction
- Ashi Girl* - I barely even remember the SFL
* The FLs in these dramas are from modern times and travel to the ancient past; in some of them the ML also travels to modern times.
