He was willing to commit sorcery (a forbidden art) to keep her alive - that's why her feelings count to him. The…
It reminds me of another Jung so min drama playful kiss. The plot was basically Jung so min character became a nurse or sth because she was chasing after a boy.
He already achieved his personal agenda - enter Songrim to be a mage and proven he is Jang Kang's worthy son.…
Now he told maidservant Kim,if he doesn't care if people acknowledge he is Jang gang's son or not, depending on his achievements. So now it feels like becoming a mage in songrim is wasted.