Male lead and female lead in arranged marriage, but she loves the second male lead

Its usually the ML that is in love with the SFL and later realizes his love for the FL. Though try out these dramas even if these are not really the same Scenario.. but maybe someone close to what you are looking for...

• Creating Destiny - FL is forced to meet and go on the arranged marriage agreement of her dad with his Bestfriend's, despite FL wanting to marry her BF.
• Leh Ratree - mostly fits the scenario with FL in a relationship with the SML, but rather than arranged marriaged, the FL is forced/contracted to the the surrogate mother for the ML's heir. So its contract baby maker, and she was forced to stay with the ML..?!
•  That Fool - ML and FL enter into a contract marriage to protect the SML reputation and hid his relationship with the FL
• Marriage Not dating - leads are in a contract dating relationship, but FL gets attracted to a SML
• My Little Bride (movie) - arranged narriaged despite FL being young, and atrracted to somone her age. But later realize her love for ML.
• Pride - leads enter into a contract dating relationship with break up role is if the ex-BF of the FL comes back

 Linus:

The King's Woman is exactly what you described. The female lead sacrifices herself and marries the ML in order to get an antidote for the poisoned SML. She views the SML as the companion and the love of her life at this time. 

Yeah, but does she fall in love with the ML and stay with him? Because that's what I want. She loves the ML first, but then as she spends time with the ML, she falls for him.

Does it matter which country it's from, and what are the language's that u know of?

Yes to King's Woman ^^ one of my favs (there's more to the story tho sooo)

You might also like Siege in Fog

 Sangmo:

Both of those have bad endings, right? 

I think it depends on what you consider as bad. I'm pretty much satisfied with the endings :)

 Ashes of love