I.e., without him, she wouldn't know how to help downtrodden mankind. If he requires her to feel for him, she requires him to do for her. This is why the allegorical marriage of materialism and altruism is a "successful match."
Reading this sentence, we are almost tempted to overlook the inherent contradiction
is "her unselfish ambitions." Contained within it, however, is the
tacit admission that even altruism is a personal ambition, i.e., a dream-ideal.