As I recall her name SJW often called her as Miss Kim, is back to her hometown. She later think/realized that she has no power to fight eventho she is B ranked, she fear fight and that fear made her unable to fight properly or use her power at max, moreover with the past experience she, Jinwoo, and others encountered in the double dungeon when they are annihilated. So after the last battle with 'new powerful' Jinwoo she decided to stop as a hunter and back to her hometown while bidding her farewell to him
I dont think they were friends, tho the girl obviously think so (or maybe think so?) Since they are member of the team and he was always got hurt even with such a big number, easy raid and weak monster. I think what JW feel toward her is gratitude and respect(?) of her always help him eventho she know he was so weak and other member belittle him even whispering bad thing about him, also back then his thought all full of funding her sister's school and mother's med bill..
He said you're the only woman friend I have like was he not friends with that other girl in the beginning of the story? Or did something happen to her that I don't remember?