Ever since I saw Paladins in Troubled Times, I've been really interested in this kind of relationship. So, I'm looking for more like this. All recommendations would be greatly appreciated.
I don't know if this fits your description but right now I am watching "The Legend of Hua Mulan" and there she falls in love with a prince from an enemy country. However, as far as I have seen it (12 episodes are subbed at the moment) she does not know that he is from this country because he pretends to be a horse merchant from another country. He, on the other hand, knows that he should not love her because she's from the enemy country but he does so nevetheless. I'd recommend you to check it out it is a really great drama, even if only 1/4 of the episodes have been subbed yet.
That fits in a general sense. Although, it's not what I truly crave for: intense, tragic but hopeful sweet. In Paladins in Troubled Times, the main girl approached the main lead as a spunky, adorable, mischievously willful thief who helped him out. And since then, they spent a brief time together, and the male lead sense that she's something he can trust and count on. She developed feelings for him as they spent time together and it's the same for him, albeit not that strongly yet, but still.... A number of events and drama happened, and to get down to it, the main girl betrayed him and indirectly caused the death of his godfather who raised him (she didn't killed him, but her betrayal let the enemy into his home which, was a sect located on top of a mountain. His godfather's death wasn't something she wanted or expected, but either way, it turns out that she was on the enemies' side all along. Unknown to the male lead, she had reasons and she's kinda torn between two people she loves (did it for her brother whom she loved dearly) to betray him, but it's something he'll never be able to accept even if he did knew (her brother is an ally of the rebel leader, someone the male lead is fighting against). And so, he vowed to get revenge for his godfather, and he was serious about it. When he met her again, he tried really tried to kill her, but he wasn't strong enough as her martial arts was stronger at the time. Even though he hated her now and wants her dead, she never stopped liking him. They make a deal, he gets to fight her 3 times (once a day), and if he can't beat her by the third day, then he'll give up, but if he can, then she won't resist him killing her. So, he trains from a manual that's rightfully his since it was his father's (was a great swordsman), and every evening or so, he fights her. With every attempt, his attacks became more and more furious, but he also grew closer to beating her until finally he became strong enough on the third try. He had the chance to kill her then, but he couldn't bring himself to do it. During the period when he was training, her personality was half as it was before she betrayed him and half melancholic but determined. She also cooked for him for the three days he trained and fought in order to keep up his strength, showing that she really cares for him. Confused, upset, and conflicted. the male lead's budding feelings that he had for her grew greatly within those 3 days. Even though he didn't killed her when he had the chance then, he said claims he won't let her off the next time. After that, numerous things happened and she ended up saving him a few times, and despite all that, he holds an abrasive and standoffish personality towards her. But that slowly and eventually fades away as the story goes on, of course. But how the drama is done between the two, in that they're both tormented by the fact they like each other, but can't be together. This is shown more strongly in the main girl who gets seriously upset and depressed, lashes out and drowns herself in alcohol. The kicker here is, the male lead seems her in these states, and in his heart, he knows it's true love that she has for him, and that also is true for him in the end. Guuh, sorry for wall of text. ANYWAYS, thanks for that rec. it might not be what I really want, but it has the theme. It might have potential to become intense.
Ok, well I don't know any drama that is similar to this one :D ... but maybe you want to check out Hua Mulan when it's fully subbed. It has only just begun and there are many things going on, I think it's gonne be great. Sorry that I couldn't be of more help!
Secret Love. Here is the plot :A devoted woman makes the ultimate sacrifice for her boyfriend, only to learn that love doesn’t always conquer all. Yoo Jeong (Hwang Jeong Eum) is a sweet, upbeat person who has always stuck by her boyfriend, Ahn Do Hoon (Bae Soo Bin), all through school as he cared for a disabled father. But Do Hoon gets into a car accident that results in the death of a woman. Unable to face her boyfriend having to go to jail for a hit-and-run accident, the self-sacrificing Yoo Jeong takes the blame for the accident and serves time in prison in his place. Min Hyeok (Ji Sung), a cold-hearted heir to a business empire, had just begun to open his heart to a woman when she is killed in the hit-and-run accident. Years later, he is engaged to Shin Se Yeon (Lee Da Hee), a congressman’s daughter. Can Yoo Jeong and Min Hyeok mend their wounded hearts and discover the real meaning of love? I think the relationship between the two leads is being enemies but I don't know if this drama is what your looking for......I'm not sure but you should try this show anyway, its right now airing and 10 ep are out.
The Princess' Man Main leads fall for each other, but their parents are enemies. Girl's father kills the guys family. The guy wants revenge against the girl and her family.

A Love To Kill The main lead's brother is heartbroken and walks off a building. The main lead wants revenge from the main girl because she caused his brother's heartache.

Athena Government agent (the guy-good guys) vs. Athena agent spy (the girl-bad guys).

Not sure about these:

King2Hearts South Korean prince and North Korean soldier. It's more political with misunderstandings rather than actual enemies.

Prosecutor Princess (Sorry About This)

All About My Romance Light and funny romantic comedy. The two leads are in different political parties. I can't get into more than that because of spoilers, but their relationship is tested more than just on a political level.

Iljimae Iljimae's father is framed as a traitor; his father is killed while his mother and sister are taken as slaves. The girl's father knowingly helped in framing Iljimae's father, although he was fallowing orders from the main culprit. Iljimae wants revenge against the people who destroyed his family.
@Archania No worries. @Happyforkoreandrama Looks like it might. I'll look into it. Thanks. @ricky I've seen Prosecutor Princess already and I guess it could fit this theme on some levels. Not fully because of the execution, but yeah. Some hit and miss, but Athena and The Princess' Mansounds right up my alley. All About My Romance too possibly when my mood is craving for romantic comedy for this type of theme. Anyhow, thanks.
Sealed With A Kiss <<<<<,