Spelling, in principle, should reflect pronunciation, but I've also read that the opposite can happen, and that the pronunciation of a word already in circulation can be changed by altering/standardising its spelling. I'm afraid I forget the publication - it was several years ago - but a striking example that was given was the word clothes, which, as it's usually pronounced now, involves a cluster of consonants which is physically awkward for an English speaker to utter. According to this book, in centuries past the word was pronounced more like close (to rhyme with rose) which is a lot easier to say even today, and the change occurred because of the standardisation of spelling.
As anyone who's handled old books knows, the genitive/possessive apostrophe did not become common practice until well into the eighteenth century, and was not fully standardised until the Victorian era. Before then, it was quite correct to write, for example, in the Articles of Union of 1707, "Her Majesties Great Seal". At that time, did people write "wifes" meaning wife's and "wives" meaning wives', or did they write "wives" for both, and did pronunciation reflect this? The construction wife's is slightly awkward to say, and so I wouldn't be surprised if it was an eighteenth century concoction.