I do not know whether it was because of the fasting (or for any other reason) that he (the Holy Prophet) refused to accept that. She raised her voice and showed annoyance to him.  

انْطَلَقَ رَسُولُ اللَّهِ ﷺ إِلَى أُمِّ أَيْمَنَ فَانْطَلَقْتُ مَعَهُ فَنَاوَلَتْهُ إِنَاءً فِيهِ شَرَابٌ قَالَ فَلاَ أَدْرِي أَصَادَفَتْهُ صَائِمًا أَوْ لَمْ يُرِدْهُ فَجَعَلَتْ تَصْخَبُ عَلَيْهِ وَتَذَمَّرُ عَلَيْهِ  

Let us visit Umm Aiman as Messenger of Allah ﷺ used to visit her. As we came to her, she wept. They (Abu Bakr and Umar) said to her: What makes you weep? What is in store (in the next world) for Allah's-Messenger ﷺ is better than (this worldly life). She said: I weep not because I am ignorant of the fact that what is in store for Messenger of Allah ﷺ (in the next world) is better than (this world), but I weep because the revelation which came from the Heaven has ceased to come. This moved both of them to tears and they began to weep along with her.  

أَبُو بَكْرٍ ؓ بَعْدَ وَفَاةِ رَسُولِ اللَّهِ ﷺ لِعُمَرَ انْطَلِقْ بِنَا إِلَى أُمِّ أَيْمَنَ نَزُورُهَا كَمَا كَانَ رَسُولُ اللَّهِ ﷺ يَزُورُهَا فَلَمَّا انْتَهَيْنَا إِلَيْهَا بَكَتْ فَقَالاَ لَهَا مَا يُبْكِيكِ مَا عِنْدَ اللَّهِ خَيْرٌ لِرَسُولِهِ ﷺ فَقَالَتْ مَا أَبْكِي أَنْ لاَ أَكُونَ أَعْلَمُ أَنَّ مَا عِنْدَ اللَّهِ خَيْرٌ لِرَسُولِهِ ﷺ وَلَكِنْ أَبْكِي أَنَّ الْوَحْىَ قَدِ انْقَطَعَ مِنَ السَّمَاءِ فَهَيَّجَتْهُمَا عَلَى الْبُكَاءِ فَجَعَلاَ يَبْكِيَانِ مَعَهَا