Moonshine and Valentine - Never any arguments but there is a misunderstanding between them at the start. They have a mature yet adorable relationship where they love each other deeply and trust each other. (One of my all time favorites!)
Go Go Squid! - No arguments between them while in a relationship, they go through a lot of struggles together but support each other. But they begin with a love/hate relationship (FL had a one sided love for ML but the ML wasn't interested), slight age gap.
Better Days - Very emotional movie but they have a great relationship where they protect each other! Really worth the watch :) happy ending
My Love, Enlighten Me - Throughout the drama they only have one argument but it is for a good reason. The show is more about chasing dreams but has a lot of romance too (And friendship)
The Princess Wei Young - This drama is a tragedy but if you don't mind that then I think you should give it a try as their relationship is beautiful.