I apologise for being pessimistic here, but I would like to point out that since he's a polite and kind person by heart, he may never really tell you if he's gradually falling out of love, or is skeptical about staying in love with you; and like you've mentioned he doesn't make you feel inferior, which is certainly not something a kind and modest person would do. So he may tell you that you drive him crazy in bed, are beautiful and make him laugh but no one else, but keeps what he doesn't like about you to himself. And the fact that he reads a lot says that he's always progressing intellectually the more he reads, and is constantly influenced by what he reads, and I hope you are cognizant of the fact that we are all fickle minded to a certain degree, so anything is possible.

But, the issue here could just be your low self esteem - however if you feel as though you're certainly no match for him and feel almost totally unsophisticated compared to him, I'd suggest you put an effort into reading what he reads sometimes to ensure you both stay on the same wavelength, as what he reads highly reflects upon what he thinks, and how he thinks. Yes, you are allowed to think for yourself and have your own sentiments. You are allowed to have different interests and ideologies and you can argue that opposites attract. But having identical interests and viewpoints keeps conflicts of interests minimal, which keeps the relationship healthy