No such episode exists, however at the end of the manga, One of Souta's friends asks him to introduce his hot sister to him. Souta responds by saying Kagome left right after graduation to get married. Kagome had moved to the feudal era permanently, and calls Sesshomaru oni-san which means brother. (Receiving identical angry glares from the two of them). Taken together we can assume they had gotten married. inuyasha the final act episode 26