This means "you came to me eventually" or "you this is kind of poetic expression. Im not suee but 내게 왔구나 you came to me This means the fact that you came to me 내게 와 주었구나 주었 means that you do something for me. So 와주었구나 implies that your coming was for me, and I should(?) thank you. 그가 와주었지만 미안하게도 나는 불편했다. I was not comfortable even he came for me Ok i can make summary that 나에게 와주다 means come for me, on the other hand 나에게 오다 means come to me.

It's a little complicated. It means you came to me literally. If someone got a crush on you and you accepted it, someone'd tell you "내게 와 주었구나".