The narrator marrying Isis, their break-up, his adventures, and their reunification may symbolize a spiritual path connecting a seeker to his spirit-soul.
This song may be catchy partly because it relates to a deep level of the soul: the initial separation from the field of unity. On the way back we may be confronted with wounds from the past.
Oh Sister, like many Dylan songs, can be interpreted on various levels: a relationship of siblings, a love affair, possibly with biographical references? From a spiritual perspective, it may be the spirit aspect addressing the soul aspect in man.
What sounds like a tragic love affair, can be seen as instructions on how to purify one's soul to regain the majestic soul-garment.
In Love Minus Zero / No Limit, Dylan abstracts from the trials and tribulations of human relationships, and points to a higher level of purity.
Love songs are well suited to relate to several levels of understanding: from erotic references to the longing for a companion, a soul mate, up to inner processes of soul and spirit that use worldly love merely as an analogy.