Yuria Sensei no Akai Ito

Fifty-year-old Yuria has a quiet life teaching embroidery classes in her home, where she lives with her writer husband and his mother. Then one day her world is turned upside down when husband has a subarachnoid hemorrhage and upon arriving at the hospital, Yuria is met by a tearful young man who announces that he is her husband's lover.
(Source: MangaUpdates)
~~ Adapted from the manga series "Yuria Sensei no Akai Ito" (ゆりあ先生の赤い糸) by Irie Kiwa (入江喜和).