Lovers - an oldie, but a pretty good fit for what you're looking for. I totally fell in love with this drama the first time I watched it. The ending could have been executed better, but it was definitely a happy one. Action, crime, romance.
Nine: 9 x Time Travel could also work. The ending will depend on how you decipher previous events. As someone who hates sad/tragic endings, and can only sometimes tolerate ambiguous endings, I was satisfied. This drama is like a puzzle. If you put it together in the right way, you'll get a happy ending. If you don't, you might get a less happy ending.
The Princess' Man - historical, romeo & juliette-esque, but far less tragic!
Time Between Dog & Wolf - an oldie but it's pretty decent!
Cruel Romance - action, crime, romance. This was really watchable with a great OTP. The male lead is a real dreamboat!
Too Late To Say I Love You - fits well with what you're looking for, however, while the ending is a happy one (nobody dies & the ML & FL reunite), the happy part is very abrupt, lasting only about 30 secs to 1 min. I was disappointed by this, but that's only because I wanted more of this amazing, passionate couple. You will not have to worry about brush lip kissing in this drama. The rest of the drama absolutely made up for the shortcomings of the ending.
The Masked Lover - fits perfectly with what you're looking for! Action, romance, two very dreamy male leads & a beautiful happy ending.