Chinese Paladin 5, Happy Ending?

Not really answering your question, but I stopped watching Chinese Paladin 5 halfway through the drama, I can't remember exactly why, but I think it dragged on. Ironically, the rating dropped to 7.3 (from like 8.2 while it was airing), so I can only imagine that the 2nd half was worse or the ending was bad (even if it was happy). Basically, I wouldn't recommend the drama, if you care a lot about latter parts of a drama or endings.

Seems like you've watched most of the good historical romance c-dramas, but maybe consider ones set in the world war periods like Battle of Changsha.

Well, it's not a happy ending. I would label it an open ending? I put a question mark because the ending for the main pairing was... bad.
Almost not like an ending or an in-need-of-a-sequel sort ending.

The main plot was not that good though. I only watched for the 2nd pairing, who has a sad ending... 
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Historical C-dramas with happy endings:

Sound of the Desert has a happy ending for the main couple, but I think a lot of viewers who have watched it also consider this drama kind of a tragedy because of the ending for the 2nd lead. (Major 2nd lead syndrome)

The Condor Heroes trilogy (Legend of the Condor Heroes, Return of the Condor Heroes, and The Heaven Sword and Dragon Sabre) all have happy endings, though they are more wuxia than standard historical. 

Legend of Hua Mulan Kinda cheesy, comedic. It actually has more to do with sewing than military tactics/fighting. Some people like it, some people don't (it's kind of a slower sort of drama)

Ban Shu Legend I enjoyed this just as much as the prequel Legend of Lu Zhen (which some people consider to have a tragic ending).
Can be viewed as a standalone drama, so you don't have to watch the prequel if you don't want to watch sad endings.
Though I think this was only partially subbed...