On the Road to -(으)로

-(으)로-(eu)ro is one of the closest things to a preposition that Korean has, but remember it isn't a preposition, it's an ending. It's basic meaning is to imply direction, something like to or towards. What helps me remember it is that it sounds a lot like "road". A road takes you to where you want to go, but it is not your destination.

When used with 하다hada / do, -(으)로-(eu)ro takes on a meaning like "go for" in English. It implies that you have made a thought out choice. For example when you're in a restaurant.

• 김치찌개로 할래요kimchijigg-e-ro halle-yo: Im going to go for the Kimchi-jigg-e
• 뼈없는 찜닭으로 할 거예요bb-yeo oem-neun jjimdalk-euro hal go-ye-yo: I'll go for the boneless jjimdalk

So just like "go for" it shows a decision or intent, while also using some words which imply movement.

But just to make it interesting we can use it with verb forms too. Just drop the -다-da, add -기-gi and -로-ro. And of course Don't forget 하다hada!

• 8시에 집에 가기로 했어요yeo-deol shi-e jip-e gagi-ro hesseo-yo: I'm going go home at 8(more lit. Im going for going home at 8)
• 술을 안마시기로 했어요sul-eul anmashi-gi-ro hesseo-yo: I've decided not to drink. (more lit. I'm going for not drinking)

So when there is a verb it means a plan or intent. It can even mean a promise, as in the second example. And in fact, instead of 하다hada you can use other verbs like 결정하다gyeol-jong hada / decide or 약속하다yaksok hada / promise or 결심하다gyeol-shim hada / to be determined to to give it that extra special meaning:

• 술을 안마시기로 결정했어요sul-eul anmashi-gi-ro gyeoljeong hesseo-yo: I have made a decision not to drink. (more lit. I've decided to go for not drinking)
• 이기기로 결심했어요i-gigi-ro gyeolshim hesseo-yo: I'm determined to win (more lit. I am determined to go for winning)

And who said Korean was difficult????