Would you like it if it was the ML that runaway from MC?
Anyway, here's some recommendation that has a similar situation:
• The First Commandment - Manhwa
• When the Killer Falls in Love - Manhwa
• The Worst Guy in the Universe - Manhwa
• Goodbye to Destiny - Manga
• Between the Lines - Manhwa
• Kakkou no Yume (MASTERPIECE, one of my favorite) - Manga
• C-Class Esper's Memorandum - Manhwa
• Mr.A's Farm (It -coule be- has multiples pair, so the one who is runaway is Mr. A, the pair of a -could be- side couple) - HOT Manhwa
• Boss Bitch Baby - Manhwa
• The Best Luck of My Life - Manhwa
• The Marriage of a Miko (Spoiler : MC not actually runaway, ML just misunderstanding the situation) - Manga
• Admiration and Longing - Manhwa
• ENNEAD (MC not actually runaway but he was thrown away as a punishment thus made him got separated with ML) - Manhwa
• Hitsuji no Kawa wo Kita Kemono - Manga
I think that's all for now. I remember I read plenty of it as I had the phase where I enjoy heartbreaking story, but my list already got too much and I need times to scroll it all over. Anyway, hope some of it will satisfy you. Happy marathon reading ε=ε=(ノ≧∇≦)ノ

can someone give me a good bl manhwa like this where the mc runaway from ml?