As Krishna (Draupadi) had repeatedly asked (in her former life) for five times saying, “Give me a husband," the greatly deity had granted her the boon accordingly. The deity himself knows the right or the wrong of this.
नैकं पतिं मे भगवान् ददातु। स चाप्येवं वरमित्यब्रवीत् तां देवो हि वेत्ता परमं यदत्र॥