Are two disputing parties, one of whom is jealous of the other to the point of estrangement, considered among those who harbor malice and whom Allah will not forgive before the advent of Ramadan?

If a friend shuns her friend and refuses to speak to her, the sin is on the one who shuns, not on the friend, especially if the latter initiated reconciliation. Efforts should be made to reconcile them, good people should mediate, and prayers for success should be offered. Excessive jealousy is reprehensible.