There are definitely people in this world who are not attracted to people who are of a dramatically different level of intelligence than them. Sometimes that means someone isn't attracted to a brilliant intellect because they feel inadequate.
My first marriage was much the same way. I didn't articulate it at the time (there were other problems), but he lost my attention... not because he couldn't keep up, but because I got tired of never being intellectually challenged. (He was and is a nice guy, just not the right one for me. I should have realized this when I discovered he owned one [count it one] book to be read for pleasure.)