And you can replace girl/she with anyone. “Don’t cross oceans for someone who won’t jump a puddle for you.”
What do you do if all your relationships/friendships are not reciprocal? If you’re the one who does everything? You end up frustrated and convinced you’re destined to live alone for the rest of your life. Then you feel imprisoned by isolation and end up living in a dungeon/hole (I think dungeon is more fitting).