A. The plaintiff and C are legally married couple who completed the marriage report on October 18, 2003, and have one child under the chain.

B. The Defendant, despite being aware of the existence of a spouse of a workplace partner C, has maintained an internal relationship, such as exchanging letters indicating that he/she is a year-based relationship from around 2009 to around 2012, or making a tour in Japan.

[Ground of recognition] Facts without dispute, entry of Gap evidence 1 to 4, purport of the whole pleadings

2. Determination

(a) Husband and wife who is responsible for the birth of loss shall live together and be responsible for supporting each other;

(Article 826 of the Civil Act). Husband and wife, as a community in which mental, physical, or economic combination is achieved, shall have the duty to cooperate and protect each other in a comprehensive manner so that marriage as a marital community is maintained, and shall have the right to such a duty.

As such, as the content of the marital or marital life maintenance obligation, the married couple bears the sexual duty that should not commit any unlawful act.

If one side of the married couple commits an unlawful act, the other side of the married couple shall be liable for damages caused by a tort against the mental suffering which the spouse has sustained.

On the other hand, a third party shall not interfere with a married couple's community life, which is the essence of the marriage, such as interfering with a couple's community life by causing a failure of a couple's community life.

In principle, a third party's act of infringing on or interfering with a marital life falling under the essence of marriage by committing an unlawful act with either side of the married couple and causing mental pain to the spouse by infringing on the rights of the spouse as the spouse.

(see, e.g., Supreme Court Decision 2013Meu2441, May 29, 2015). In light of the foregoing legal doctrine, the health stand in the instant case, and according to the above recognition, the Defendant committed an unlawful act, such as having knowledge that C is a spouse, with knowledge that C is a person with a spouse.