Faithful?

It should also be realised the husband is required to be faithful in marriage as the wife must. The punishment for adultery of a married person, male or female, under the Shari’ah is death. The fact that the punishment may not be applied in this world, does not make the sin any less in the sight of Allah. A sin that is not expiated in this world is after all going to follow a person to the grave.
Therefore the husband should not fail to follow Allah’s command in the Qur’an:

"Tell the believing men to lower their gaze and to be mindful of their chastity: verily this will be most conductive to their purity (and) verily Allah is aware of all that they do."[Qur’an 24:30]

Those married men who cruise around in their cars looking for school girls to pick up are surely disgracing themselves, and forfeiting all right to require chastity of their wives.
If for some reason, the husband cannot manage with his first wife but does not want to divorce her, he is not prohibited from contracting another marriage, provided it is done in a legal and honorable way.

The permission to marry more then one wife at a time is however conditional:

".......if you fear you cannot do justice between them, then marry only one." [Qur’an 4:3]

This condition is often taken very lightly in some countries, where polygamy has long been a social custom. No words in the Qur’an, however, are without meaning, this verse should not be taken lightly. A weak husband will not be respected and will not act fairly between his wives, whereby, his marrying more then one is likely to lead to injustice, constant disharmony and the break up of his family. This is not in his interests or theirs or in the interests of the Muslim Ummah.
If having married more then one, however, a husband finds his heart inclining to one at the expense of the other, he is warned that this inclination should not reach the stage of neglect of the needs of the other wife:

"And you will not be able to treat your wives with equal justice however much you desire it.
But do not incline towards one to the exclusion of the other, leaving her as it were in suspense." [Qur’an 4:29]

This warning against injustice is strongly reinforced by the Hadith in which Abu Hurairah (raa) reported the Prophet (saws) as saying:
"Whoever has two wives and does not treat them equally, shall come on the day of resurrection with half his body hanging down." [Abu Da’ud, Nasa’i, and Ibn Majah]