According to Osho, viraha is love-longing—the searing, prayerful yearning for the hidden Beloved that ripens the lover for union (milan). It is preparation and purifying fire: tears, trial, and burning that melt the ego until one becomes ash, from which union dawns. To know viraha you must love and participate—call, seek, and let the heart ache until the veil lifts.
It’s the deep ache of missing and calling the Divine that cleans your heart so real union can happen.