I have never heard that expression, but I think it probably means “you should be devoted to reading like you would be devoted to a wife; your books should be constantly with you.”

Your teacher "has a way with words" <- a common phrase you will hear. I think they are using definition (2) to mean keep referring to your books be in harmony with them and possibly also as in definition (1) join in marriage. "I was married in church" synonyms: get/be married, wed, be wed, become man and wife, plight/pledge one's troth; More 2. join together; combine harmoniously. "the show marries poetry with art"

I think it means: you should engage to your books.notice them and they would be your priority.