In short, 一人の～ sounds more specific and ～一人 more general. 一人の女性 often translates into "a certain woman".
If I heard these phrases, I'd take #1 as "a man who loved (only) one woman" but #2 as "men who loved (only) one woman". That is because 一人の女性 probably means a specific woman, so I think that the man is specific, too. On the ...