There are several options. Some common places are dedicated manhwa websites or apps. For example, Lezhin Comics often has a good selection of romance manhwa. Also, check out Tapas as they might have what you're looking for.
For a romance manhwa to be good, it needs a compelling storyline. This could involve obstacles the couple has to overcome or a unique setting. Also, the art style plays a big role in creating the romantic atmosphere.
One popular ability manhwa fanfiction is 'The Awakened One's Journey'. It focuses on a character who discovers a unique ability and has to navigate a dangerous world. Another great one could be 'Ability Wars' which has intense battles between characters with different powers. And 'Mystic Abilities' is also interesting as it delves into the origin of these special abilities in the manhwa world.