So, Im looking for romances involving a Male MC who is considered low-class/caste or a peasant, or poor, or (I think we get the idea) who ends up in some sort of romantic scenario with a female who is considered upper-class/caste or a noble, or rich, or (again, I think we get the idea).

As far as the roles go, Im pretty set on the male being the lowclass/poor and the female being the upperclass/rich, because the scenario, in my opinion, means more that way, like, if a rich guy or upper class guy fraternizes with a lower class woman, he tends to just be treated like a philanderer, or a playboy, or just playing around, etc.  where-as with an upper class or right woman, it tends to bring in more actual social implications, people usually look down on this type of relationship, or try to put a stop to it, etc, which makes the situation a better watch overall, in my opinion.   

As for the male, I do not like overly a-hole type males, I mean, its one thing if he is just kind of anti-social, or a bit of a delinquent/butt-munch (hopefully that language isn't too strong), or something, but I don't like guys who are just straight-up mean people.   Like, Im ok with something who's a bit mean, like Eun Dae Gu from You're All Surrounded, but not...well, I cant really think of anyone to describe the other way, because I drop anything as soon as I see that kind of MC.

I don't mind any sort of setting, I don't mind modern setting, or period, I dont mind any sort of theme, but I notice that I tend to not like Medical stuff as much.

Sorry if this sounds too specific, and I appreciate any time you spent reading this.

Tatta Hitotsu no Koi (2006)

That's the best one I can come up with right now.
High Society is one of those! 
I'm recommending Ruler of Your Own World. The guy's an ex-con (he's a pickpocket) while the girl's the daughter of a real estate boss (she's a bit of a nonconformist though, and she aspires to be a professional musician rather than getting a respectable job like what her parents want her to). The acting is top-notch and the story is solid (I don't remember any draggy parts), but since it's from 2002, the production value is comparatively low and might put some people off, especially if you're more used to newer Korean dramas.
That Fool - average joe, looked down upon postal worker develops relationship with A-class celebrity. The nicest guy I've ever come across in kdrama's! Think you would really enjoy it :-)
Only ones i can think of apart from what have already been mentioned is History of the Salaryman and Take Care of the Young Lady
Bijo to Star no 99 nichi: Hallyu star actress comes to Japan to film a drama, where she is assigned a bodyguard who is just doing it as a job & would much rather be pursuing his interest in astronomy.