Fowler himself admits that he might not understand Phuong, his young lover. He certainly doesn't give us much insight into her interior life. Then again, he doesn't converse with her the way he does with others.
No surprise, but his own admission, he's not interested in her interests. "Like any other woman," Fowler muses, "she rather have a good … [Anglo-Saxon swear word]" than have someone look after her interests (184.108.40.206).
Neither he nor we know whether she's happy, what she really wants out of life, or what she'd choose if she had more choices. Upon Phuong's hearing of Pyle's death, "there was no scene, no tears, just thought—the long private thought of somebody who has to alter a whole course of life" (1.1.130).
So what do we know about Phuong? She used to be a dancer. Now she's Fowler's "date every night" (220.127.116.11). She stays with Fowler because he seems to be a loyal and secure man who can give her life stability and comfort. She'd like to marry him. When that looks to be impossible, she leaves him for Pyle. When Pyle dies, she returns to Fowler.
Her interests, so far as well can tell, involve seeing movies at the cinema, news about the royal family, the prospect of seeing skyscrapers, and the hope for marriage to a faithful man. This isn't to say that she's a superficial person, it's just that Fowler gives us only a superficial report.