I don't know. Perhaps Clive just wasn't into the brainy sort. I mean, take into consideration his friendship with Risley. Undoubtedly intelligent and conveniently homosexual, but there's no mention of any attraction.

Actually, I find that Maurice and Clive are rather similar. While Maurice feels he must strive for normalcy, much of Clive's self-assurance is a bluff, then and later. Perhaps if Maurice had come to terms with his sexuality earlier and Clive had later, then their roles would have reversed as well.