i dont know if you watch historical dramas but empress ki ia a good choice. i adore love triangles and court drama so its good.
action dramas would be king 2 hearts. it also has some romance in it.
circle- two worlds connected is only action and a very tiny amount of romance. still worth the watch tho.
queen inhyun's man is a time traveling drama so really interesting and has a lot of romance.
splash splash love is another drama about time travel but each episode is only 11 ish minutes cause it's a webdrama.
a-teen is a good webdrama if u like shorter eps. seventeen sang a ost for it and april's nauen is in it. u can find it on youtube under global playlist.
let me know if u need more.