There are a lot of characters in Young Sheldon who seem to mysteriously disappear and Pastor Rob is one of them. We first meet him in season five but after his last appearance in season six, he’s not seen again, not even for a cameo in the final episode.
Whilst Mary was hesitant about his alternative method of teaching children about religion at first, they soon became close friends to the point where George even suspected they could be having an affair. Funnily enough, one of the last times we see Mary and Pastor Rob together could explain his sudden disappearance from Young Sheldon, as well as what he went on to do.
Via Netflix
Pastor Rob meets with Mary at Lulu’s Corner cafe and reveals to her that he’s been offered a job at First Baptist Church in Little Rock Arkansas. He’s not sure whether to take the job and she tells him to follow his heart. He later sees George and Mary fighting over their joint suspected affairs and overall marital problems.
His disappearance in season six and noticeable absence from George’s funeral seem to heavily suggest that he did actually take the job offer and moved to Arkansas. He might have decided that it was best to leave without saying a proper goodbye to Mary due to George’s suspicions, hence why we never got a confirmed ending for him.
