ML gives up on his crush?

 Marfi09:

ml gives up on his crush of 2nd fml at early stages

• Coffee Prince
• Gu Family Book
• The Great Seducer

 Marfi09:

he tries to win heart of fml for long time and finally decides to give up on her like I Need Romance 3

I didn't interpret the ML's actions in INR3 as giving up on the FL. He recognized that the FL did not appreciate him, was not treating him well, and refused to acknowledge her feelings for him. He gave her an ultimatum that she had to choose him or the SML and he followed through with it, but he believed she would figure out her feelings eventually and he was right. 

These MLs never give up their feelings for the FL, but they try to make a relationship work with someone else, in most cases because they feel obligated to do so but in some cases because they believe the FL will never return their feelings or they are denying their feelings for the FL:

• Wednesday 3:30 PM - the FL tries to win back her ex and the ML has a crush on the SFL at the beginning of the drama, but the ML falls for the FL while helping her make her ex jealous; the FL also develops feelings for the ML but doesn't fully realize it at the time; the SFL comes back and tells the ML that she has a brain tumour and guilts him into agreeing to date her and later puts him in a situation where he's basically forced to be engaged to her
• In Time With You - the ML has had feelings for the FL since they were in high school but for complicated reasons he approached her as a friend and swore he'd never have feelings for her; he becomes her best friend and they both date other people, but their "friendship" ruins their romantic relationships; the ML tries to deny his feelings for the FL in order to preserve their friendship because he's afraid of losing the FL
• The Imperial Doctress - after enduring many hardships with the FL, he allows her to live peacefully in seclusion while he must return to the palace to rule and restore order to the country; after many years when his son is ready to inherit the throne he finally 
• 100 Days My Prince - the ML is the crown prince who had a political marriage but never consummated it; he has amnesia following an accident and does not remember his identity; due to certain circumstances, he ends up marrying the FL to save her from becoming an awful old man's concubine; later his princess consort's scheming father find him and lies, telling him that he has a wife and that she is pregnant with his child; he feels obligated to return to the palace
• Queen for Seven Days - after many hardships the ML and FL never give up their feelings for each other, but they agree to live separate lives for the good of the country so the ML can rule well; they only meet again just before their deaths; he presumably had a different empress and harem
• Accidentally in Love - the SFL becomes suicidal after finding out that the ML and FL are dating, and her friend convinces the ML that she will kill herself if the ML does not marry her; as a result, he feels obliged to agree to marry her
• The Princess Wei Young - the ML begs the SML to save the FL's life and promises he will do whatever the SML asks in return; the SML forces him to promise to marry the SFL; he has no other choice but to agree
• Love That Makes You Cry - I don't remember the exact details, but I think the SFL was suicidal and the ML didn't want to risk jeopardizing her mental health so he continued to date her even when he admitted that he was in love with the FL

The ML steps back from the FL or pushes her away to protect her because he believes it would be harmful to her if they were together:

• Just Between Lovers - the ML pushes the FL away and distances himself from her because he believes he's not good enough for her
• Sungkyunkwan Scandal - the ML distances himself from the FL because he thinks she's a boy and he doesn't want to endanger her by pulling her into a scandal involving a homosexual relationship, which was taboo at the time
• Healer - the ML pushes the FL away because he's afraid that he'll hurt her / being in a relationship with him will put her in danger
• The Smile Has Left Your Eyes - the villain tricks the ML into believing that the FL is his biological sister; he breaks up with the FL and takes drastic measures to protect her before further distancing himself from her

Others:

• Love in the Moonlight - the ML is the crown prince and the FL eventually finds out that her long-lost father was the lead rebel who tried to overthrow the king; realizing that her presence puts the ML in danger, the FL runs away; when he tries to meet her again, she pretends to be afraid of him; the ML had previously promised he would believe anything she told him, and so in this case, understanding that she is desperate, he tells her he will believe the charade that she is afraid of him and will let her leave
• Hi! School - Love On - the ML prioritized the FL's safety over his happiness / ability to be with her; while the FL originally lived with the ML, he agreed that she should live with the SML / his love rival during a time when she was in danger