ML is poor and struggling

I'm looking for a Kdrama where the ML is poor, struggles to live(financially, mentally, emotionally, physically.....). He shows frustration at times. He's mean/cold to others or the FL but then as time goes on, he changes. Also the FL is someone who is having a better/happier life than the ML. If no Kdramas match both of my needs, then just the description of the ML is good enough. 

I have already seen Just between lovers.   

 KenTaro:

a Kdrama where the ML is poor, struggles to live(financially, mentally, emotionally, physically.....). He shows frustration at times. He's mean/cold to others or the FL but then as time goes on, he changes. Also the FL is someone who is having a better/happier life than the ML.

• The Smile Has Left Your Eyes - The ML starts out cold (although he is very capable of being charming in order to manipulate others) and, for lack of a better word, sociopathic. He's capable of holding down a job and making money... for a short amount of time. But he plays reckless games that quickly upend that apparent normalcy and, in his own words, he doesn't know how to be a good person. 

 KenTaro:

If no Kdramas match both of my needs, then just the description of the ML is good enough. 

• Bring It On, Ghost - The ML has the ability to see ghosts, and he hates it. He's pretty much on his own and struggling to save up to pay someone to take away that ability... by taking on jobs to fight ghosts. While he usually isn't out-and-out mean, he starts out fairly selfish and focused on his own needs, and over time he opens up and starts caring about others more. The FL isn't exactly having a better or happier life than him, especially in the beginning before she meets him, because she's a ghost.
• 100 Days My Prince - The ML is the crown prince but gets into an accident and loses his memory. He is arrogant and rude, but also alone and incapable of fending for himself in the real world. From what I remember, the FL was born into a noble family but had to go into hiding and lives as a peasant. She's not alone and can look after herself, but she doesn't have it easy and then the ML shows up.
• Dream High - This one is iffy. One of the MLs is a poor country bumpkin who wants to become a singer. The FL convinces him to leave his mother and home behind to go to a school for aspiring performers in order to ensure her own spot. Unrequited love and an accident add to his struggles. Most of the time the FL is the cold and mean one while this ML is innocent and sweet, but iirc there are times when he struggles and is mean or cold. But isn't not really one of those story arcs where the cold/mean guy opens up and becomes warm and nice. The FL is abandoned by her father (who is running from debt collectors), loses her home and becomes responsible for looking after her little sister. So she's not exactly happier or better off.

The ML is not poor and the FL is not financially better off than him, but otherwise your criteria are met (although the ML's biggest change really only happens after the ML and FL separate in the end):

• Cheese in the Trap
• Moon Lovers: Scarlet Heart Ryeo

The Golden Spoon- Their fortunes get reversed at some point but this fits

 KenTaro:

I'm looking for a Kdrama where the ML is poor, struggles to live(financially, mentally, emotionally, physically.....).

• Moment at Eighteen ML is poor and lives on his own to attend school, while his mother works elsewhere. He is a new transfer, and there are rumors surrounding his transfer so he is bullied. FL is from a well-to-do family, smart and kind.
• At a Distance, Spring Is Green ML is from a rich family who doesn't want him around. SML provides friendship and stability. FL plays less of a role in this one.
• Twenty-Five Twenty-One ML's family was rich until his family went bankrupt. Now each family member is scattered in different cities with his father running away from creditors. FL and ML create a tight-knit a group of friends with others.
•  Bossam: Steal the Fate ML is poor and his main way of making money was as a bossam-man (or kidnapper of widows). [A single man or widower would kidnap the widow and marry her. Some of the kidnappings were agreed upon in advance and others were by force. IMDB]. When he accidentally kidnaps the FL, life was never the same.