According to Vedic customs : 

there is no such thing as second marriage

The mandatory conditions are:

He or She should not have been married to another earlier...so there is no such thing as second marriage 

Vedas' view on marriage and responsibility after marriage?

Rigved: 2/35/4:-The young men and young woman should marry whose hearts are pure and clean. A man possessing physical strength should brightened his family by getting married.

Athavaved 7/36/1:-Let us husband and wife look at each other with gaze of love., always speak sweet words, reside in each other’s heart. Let us be two bodies but with one mind only.

Atharva ved 14/1/52:-O wife! God has handed you over me. The responsibility of maintaining you lies with me. lets both have children and live up to 100 years.

Rig ved:10/85/46:-O daughter in law! lead your life in such a way that your mother in laws, father in laws sister-in -laws, brother-in -laws. All respect and honour you.

Atharava ved :14/1/43:-When the ocean created the rain (through evaporation of water into clouds), the river gets the water .i.e the ocean control the river. Similarly o wife! you to make entire family happy by becoming owner of the house.

Atharava ved14/2/17:- A bride! By your pleasant nature, do good of family members with a pure heart. That will increase happiness and wealth in the home.

Yajur ved: 8/63:-To run the household properly men must earn gold, animal and money by their efforts. The household is not complete without them. The progress of family life lies in diligent work.

Atharava ved 7/17/1:-Let the household by their diligence and god’s grace achieve happiness through money and strength.

Atharava ved: 14/1/27:-The man becomes impure who make use of the money and material brought by a woman in other words to take dowry is a great sin.

Yajur ved 15/59:-Benevolent women carry out every work with home with interest. they should not be lazy for any work. They educate other women about the proper conduct of the house as is done by every women of learning and excellence.

Yajur ved: 35/21:- The women is worthy of running a house who has forgiveness like earth and is able to remove the faults of others.

Rig ved: 1/164/40:-Women EducationThe mother should become knowledgeable to make their children properly educated. The glory of society increases when a woman produce children after marriage with men of good conduct and make their children cultured. Her sacrifice is as pure as of cows.

Yajur ved: 19/39:-Every good house holder must fulfill his duty to make his sons and daughters learned, graceful, and in strong in character through brahmacharya, good conduct and education.

Yajur ved 33/77:-For the benefit and welfare of the children their parents should make them spirituality strong by giving spiritual and other excellent education.
Atharva ved: 9/6/ (3) (7)O good householder man! You should first feed the athithi and the guest who comes unannounced and then eat.

Atharva ved: 7/30/1:-Man should perform such a good deeds as will give him the love of his mother, father and spiritual teachers.

Arhatva ved: 7/60/4:-All the member of family should earn and be happy. They should not be upset with hunger and thirst nor should they be afraid of each other.
Atharava ved: 20/92/5:-May we along with our sons, daughter, brothers and friends always be involve in deeds for the progress of the soul

 Firstly when getting married both should make as sure as possible that they suit each other as perfectly as possible then and only then get married ...but if later finding that they are not suited to each other due to unforeseen circumstances then split but both then should stay single.

• You have one chance and if finding later that the difference showed up that they could not live with each other then split but then stay single as you have had your chance.