The gemara discusses various ways to disprove the opinion of Rabbi Eliezer, that גירושי חוץ/גירושין על מנת (either a divorce that does not work for one person, or a divorce that's made on condition that the lady won't marry a specific person or persons) works, on Gitin 83a.
One of these is from Rabbi Yosi Haglili:
נענה ר' יוסי הגלילי ואמר היכן מצינו אסור לזה ומותר לזה האסור אסור לכל והמותר מותר לכל ולא והרי תרומה וקדשים שאסורה לזה ומותרת לזה באיסור אשה קא אמרינן והרי עריות באישות קאמרינן הרי אשת איש היינו פירכא
R. Jose the Galilean argued as follows: Where do we find that the same thing should be forbidden to one and permitted to another? What is forbidden is forbidden to all and what is permitted is permitted to all’. Is that so? What of terumah and holy meats which are forbidden to one class and permitted to another? — We are speaking of sexual prohibitions. But what of forbidden degrees of consanguinity? — We speak of marriage. But there is the case of a married woman? — This is the flaw in the argument.
(Soncino translation)
Following the (very quick) arguments of this gemara tell us that עריות were held up as the example of something that is אסור לזה ומותר לזה, something that is forbidden to one and permitted to another (I can't marry my sister, but others can), so we came back and said no, we're talking about prohibitions that are caused by marriage (see Rashi).
What is a case of אישות that is האסור אסור לכל?
Obviously, we can't use אשת איש, as that is the final question that's brought against Rabbi Yosi Haglili; but what case of a marriage-created prohibition is there that the prohibition is equal to all? Take אשת אביו, a father's wife, for example. She's prohibited to the son of her husband, but is still permitted to everyone else on the termination of her first marriage. I couldn't find a case of an איסור אישות that is האסור אסור לכל.
Is there one?