Why does 葛藤(갈등) mean 'conflict' or 'troubles'?
The Wiktionary page for 葛藤 says:

Etymology: From the tendency of the vines of kudzu and rattan to become entangled.

No citation is provided, however.
The Korean Wikipedia page for 갈등 says something similar:

어원: 왼쪽으로 감아 자라나는 칡과 오른쪽으로 감아 자나라는 등나무가 서로 얽히고 설킨 모습에서 유래.
Etymology: It is derived from the shape of the wisteria that is wrapped to the left and the wisteria which is wrapped to the right and entwined to the right. (Google Translate)

Again, no citation is provided, unfortunately.