Daas Yochid,
I was saying that if he saw someplace that Noshim are indeed Patur, the only context he would have seen it would be that it is usually not her Chiyuv, unless she’s living alone.
As for the Gemara, as you said, it was not a Hava Amina, only a question as to why it is not the case. The Gemara in Kedushin, though, is talking before we established that Zman Grama is a Ptur.