-으려다 catches an action mid-intention and cuts it off: 이것만 먹으려다 갑자기 밥 데워 먹고 그럴 때가 있죠 'sometimes I mean to eat just this and end up reheating rice too.' Most of these lines are captions describing exactly that moment of interruption — 먹으려다 눈이 딱...! 'about to eat, then their eyes meet.' It always implies the plan did not survive contact with what happened next.