In Hinduism, the bond of marriage has a great importance. Marriage is seen as a way to achieve Dharma, Artha, Kama, Moksha. Marrying once/monogamy is given an importance. Monogamy is one of the reasons which made Sri Rama a model for our generations.
Sri Chandrasekharendra Saraswati Mahaswami (Kanchi Periyava) while explaining the greatness of marriage in Hinduism:
In our religion the man-wife relationship is not concerned with the mundane alone. It serves the Atman as well as the good of mankind. In other religions too marriages are conducted, say, in a church with God as witness. But ideal of marriage is not as lofty as ours. The purpose of marriage in our religion is to purify the husband further and to impact the wife fullness as his devoted and self-effacing companion. There is no such high purpose in the marriage of other religion. In other countries the man-woman relationship is akin to a family or social contract. Here it is an Atman connection. But this very connection is a means of disconnection also of freeing the Atman, the self, from the bondage of worldly existence. There is no room for divorce in it. Even to think of it is sinful.
An excerpt from Hindu Dharma: The universal way of life.
Manu states the importance of marriage and bestowal of a bride in a marriage as follows:
Let no intelligent man, after having given his daughter to one man, give her again to another; for he who gives and then gives is guilty of deceit. (Manu 9;71)
sakṛdaṃśo nipatati sakṛt kanyā pradīyate |
sakṛdāha dadānīti trīṇyetāni satāṃ sakṛt || 9.47 ||
Once is the partition of inheritance made,once is a maiden given away; once does one say ‘I give’; each of these three comes only once.
We all know that, there is no concept of "divorce" in Hinduism.
Yes, the concept of divorce and remarriage are very rare. Even though Hindu dharma gives much importance to the bond of marriage, it has given certain conditions under which divorce and remarriage is allowed. These must not be taken advantage of to annul the marriage.
In present social conditions, divorce or remarriage is considered as an anathema by most orthodox Hindus. But only some knew that there are certain conditions under which annulment of marriage and divorce is allowed.
But while he is explaining about annulment of marriage:
vidhivat pratigṛhyāpi tyajet kanyāṃ vigarhitām |
vyādhitāṃ vipraduṣṭāṃ vā chadmanā copapāditām || 72 ||
Though a man may have accepted a damsel in due form, he may
abandon her if she be blemished, diseased, or deflowered, and if she
has been given with fraud.
yastu doṣavatīṃ kanyāmanākhyāyaupapādayet |
tasya tad vitathaṃ kuryāt kanyādāturdurātmanaḥ || 73 ||
If anybody gives away a maiden possessing blemishes without
declaring them, the bridegroom may annul that contract with the evil-minded
giver. (Manu 9;73.)
Similarly in Yajnyavalkya Smriti:
If a man gives away a girl without mentioning her defects, he should be fined with the highest amercement; but the man that abandons a faultless girl betrothed to him should be punished; and if he falsely attributes defects to her, he should be fined one hundred. (1.66)
In Vishnu Smriti:
He who forsakes a faultless wife should be punished like a thief.
If there is a lack of Harmony between husband and wife, then divorce is allowed.
For one year let a husband bear with a wife who hates him; but after
that let him deprive her of her [share] of the property and cease to live
with her. [But he should still make arrangements for her clothing and
food.] (Manu 9;77.)
Alcoholism in either parties is a justification for divorce:
She who drinks spiritous liquor, is of bad conduct, rebellious,
diseased (with leprosy), violent, or wasteful of money, may at any
time be superseded by another wife. (Manu 9;80)
One who drinks wine, or is diseased, or guileful, or barren, or destructive of wealth, or harsh-tongued, or brings forth only female children*, or bears malice towards her man,—shall be superseded. (Yajnyavalkya 1.73)
Conditions of a remarriage:
If the maiden is married to blemished man without his declaring them.
In Narada Smriti:
When a faultless maiden has been married to a man who has a blemish
unknown before the marriage, and does not take to another man after
discovering it, shall be enjoined to do so by her relatives. If she has no
relations living she may go to live with another man of her own
accord. (12;96)
In case of prolonged absence of husband or disappearance of husband.
If the husband went abroad for some sacred duty, the wife should wait
for him eight years, if he went for acquiring learning or fame six years
and if he went for pleasure three years. [Thereafter she may remarry
without incurring any sin or guilt.] (Manu 9;76)
If the husband becomes a monk and renounces the world.
If the husband is untraceable, dead, renounced the world, impotent or
degraded - in these cases of emergency a woman can remarry.
(Parashara 28)
When the husband becomes impotent and the wife is still young.
If a man is unable to have sexual relations with his wife, then she may
divorce him and take another husband. (Narada 12;18.)
If the husband is untraceable, dead, renounced the world, impotent or
degraded - in these cases of emergency a woman can remarry.
(Parashara 28)
Legal reasons for divorce by men:
- If the wife squanders his property.
- If the wife makes an attempt on the husband's life.
- If the wife continually shows him malice.
- If the wife slanders her husband.
To sum up the reasons for remarriage:
In both the parties:
- Affliction with a chronic or disgusting disease
- Deformity
- Madness
- Inability to have sexual relations
In a man:
- Committing of a crime (grave sin) for which loss of caste is the penalty.
- If the groom has forsaken his family.
In a woman:
- Loss of virginity [that was not previously declared]
Above reasons should not be taken advantage of gratuitously. These are applicable in extreme situations only.
So by above verses, it is clear that remarriage of innocent men and women is allowed. A marriage which happened under false pretences can be annulled.
*A women who gives birth to female children only should not be abandoned because female chromosomes do not have a role in deciding the gender of the child. It is the male chromosome which decides the gender of a new born baby..
** The word 'superseding' should be understood as divorce according to present social conditions. In ancient days, polygamy was allowed. But in present days, polygamy is not allowed (eg: In India, it is a crime if a Hindu marries multiple women).