When living with the practices of the modern world, the presence or absence of love in a marriage is a private affair between the married people, and it cannot be a criminal offence if one of them decides that the love between them is lost and strikes out for an extra-marital affair. The only one who has a right to feel affected is the spouse who has been cheated, and he/she is the one who can take further steps - such as filing for separation, seeking alimony, etc. However, when nations and laws get guided (or forced) by religious considerations, then society steps in and decides what is wrong and what is right, and specifically this case of extra-marital affairs is deemed adultery, and there can be numerous punishments.
In the case of societies run on strong Islamic laws, there are severe laws against adultery, which can be extremely barbaric such as the one followed by the Taliban, and more so by the recent terror Islamic State, where a woman could be accused of adultery and sentenced to be stoned to death (with lashes happening before that), and men can also be accused and sentenced for the same 'crime'. However, it was surprising that a country seen to be extremely developed, such as South Korea had a similar law on its books, with the sentence for adultery being 2 years in prison. Even though being sent to jail was rare, there were numerous people charged with the law. Finally the courts have realized that an affair is not a criminal act, and has decided to drop the law. (
link to article):
A South Korean court on Thursday abolished a 62-year-old law that criminalized extramarital affairs, and the stock price of a prominent condom maker immediately shot up 15%.
The Constitutional Court's ruling that the law suppressed personal freedoms could affect many of the more than 5,400 people who have been charged with adultery since 2008, when the court earlier upheld the legislation, according to court law.
Any current charges against those people could be thrown out and those who have received guilty verdicts will be eligible for retrials, according to a court official who declined to be named, citing office rules.
Under the law, having sex with a married person who is not your spouse was punishable by up to two years in prison. Nearly 53,000 South Koreans have been indicted on adultery charges since 1985, but prison terms have been rare.
The co-relation was interesting though. With the striking down of this law, the share price of a leading condom maker shot up significantly.