하다 말아서 그런가?
Is it like that because I stopped doing it and left it unfinished?

하다(가) 말다 : stop 

V + -다(가) (with 가 optionally deleted) followed by 말다
cease, desist; does (a while) then stops; stops/hesitates in the middle of doing, meaning to stop in mid-action, or drop what one is doing in favor of a new action.

e.g.
비가 오다 말았어요
It was raining for a while but the rain had stopped.

그런가 = 그러한가 << 그러하다 + ㄴ가
그러하다 : like that
ㄴ가 : interrogative suffix for self question.