Richard Churchill in Half of a Yellow Sun

After more than 60 pages, I now think I’ve got more into the story of Half of a Yellow Sun.
A convenient way to speak of the characters of Half of a Yellow Sun is to place at the centre of the novel the twin sisters Olanna and Kainene. Olanna is the beautiful one, “illogically beautiful”, gentle, charming, almost perfect, and interested in politics. Kainene is the skinny and ugly one, independent, proud, haughty, mysterious and enchanting.
Olanna is in a relationship with Odenigbo—the professor, the nationalist, the proud black/ Nigerian/ Igbo man, the radical of the book. Working for Odenigbo is Ugwu, a docile, ignorant houseboy that is 1 of the important characters.
Kainene is involved with Richard Churchill—a white journalist who comes to Nigeria because of his interest in Igbo art. 
Other characters are connected to either or both of Olanna and Kainene. But we can speak of them some other time (if I want to).
The 1 thing that bothers me right now is Richard. He must be the weakest man I’ve encountered in literature. As a writer, he hasn’t produced anything; he wanders around, confused and uncertain about himself. At parties he feels out of place; with people he is awkward and tries to be funny, in vain (preparing a joke and using it on different people). He’s also weak as a man. Before being enamoured with Kainene, he’s with Susan, a racist, condescending and trivial-minded woman. He never seems to speak up and lets Susan boss him around—like she wants him to move in with her so he does, though he doesn’t want to, or she wants him to go to parties that he doesn’t enjoy and talk to people that he has no interest in, so he does. The only “rebellion” is when he breaks up with her because of Kainene. 
Even in bed, Richard isn’t adequate. He often has problems and cannot quite satisfy Kainene. 
Worst of all, he is weak, unable to stand up for anything, and unable to defend his woman and their relationship when someone insults Kainene right in front of him. He stands there, helpless, like a loser. 
I don’t understand what Kainene sees in him.