Winning a Spousal Affair Lawsuit Without Decisive Proof

When this case first reached me, the client had already gone through one round of disappointment. She sensed her spouse's infidelity but lacked clear-cut evidence in hand. There was no decisive photo, no hotel-entry footage. She had been told elsewhere that "this is going to be difficult." Sitting across from her, I re-organized her statements and the circumstantial materials, and I judged that there were definite points where the other side's testimony would unravel. This article puts into general legal information the trajectory by which we secured a victory for the client at both the first instance and the appeal.

In adultery lawsuits the most frequent question is whether there is "decisive evidence." But in typical practice, cases that close on a single piece of decisive evidence are not common. Most cases are reconstructed from a combination of circumstantial materials such as the following.

• Position information that lines up by date (vehicle dashcams, highway-pass logs, transit-card records)
• Patterns of card use and account transfers over time and amount
• Time distribution of messenger and SNS activity
• Time points that diverge from the spouse's habitual routine
• Statements your spouse made to your family or acquaintances and when they were made

When these materials are aligned cleanly on a time axis, it becomes very hard for the other side to maintain a consistent narrative in court. This case proceeded along exactly that flow.

In this case, the other side at first strongly denied any relationship. But once we presented the facts organized along a time axis, the testimony began to shift in stages. From "a stranger" to "I knew them, that was all," and from "a casual acquaintance" to "one-off." Typically, this kind of stepwise retreat leaves a decisive flaw in the credibility of the testimony in court.

The first-instance court awarded alimony of 25 million won, finding to the effect that adultery is a tortious act that infringes on the essence of marriage, and that the defendant's posture could not be seen as genuine contrition.

The other side appealed on the ground that "the evidence is insufficient." But the appellate court found the first-instance ruling correct and dismissed the appeal in its entirety. When the first-instance conclusion is preserved on appeal, that typically means the skeleton of the facts was built solidly at first instance. A case that survives the appeal without the client submitting new decisive evidence is a signal that the circumstantial alignment was good from the start.

Factors that were either expressly cited in the judgment or are typically recognized for alimony can be summarized as follows.

The alimony amount itself varies sharply with the facts and evidence. The 25 million won in this case carries meaning less in the figure itself and more in the fact that it was recognized at both instances despite the client coming in with the diagnosis of "decisive evidence is lacking."

When I first saw the materials the client brought in, I shared the diagnosis of others on the point that "there is no single decisive piece." What I read differently was not the "quantity" of the materials but the "way they were aligned." Once the patterns of time, place, and amount were rebuilt, the case clearly contained moments the other side could not avoid breaking. Turning those moments into core questions for cross-examination is, I believe, the role of counsel.

If you feel that the evidence is insufficient, here are items you can check yourself first.

1. Write your spouse's one-week routine onto a time axis (departure, return, errands).
2. Lay out card-use history and account transfers in one monthly page.
3. Organize what your spouse said to your family or acquaintances (date, gist).
4. Preserve the metadata of photos and videos on your phone as is.
5. Write down each "odd moment" you noticed - memory fades with time.

Whether these materials are sufficient depends on how they are aligned. You can review the alignment direction of the materials you have at starting a chat consultation now.

Q. I have been told elsewhere that "there is no decisive evidence." Should I give up? A. The absence of decisive evidence does not equal an inability to litigate; that is the typical flow. When circumstantial materials, the accumulation of changes in the other side's testimony, and objective position information are combined, many cases have their facts reconstructed. Outcomes vary with the facts and evidence, so individual review is necessary.

Q. The other side claims it was "a casual acquaintance." How do we counter that? A. Typically, the accumulation of routine, expenditure, and contact frequency by time point weakens the credibility of the casual-acquaintance claim. Patterns accumulated often function as a stronger signal than any single piece of evidence.

Q. Is the appeal likely to flip the result? A. The more solid the first-instance facts, the more often the appeal preserves the conclusion. Without new evidence, it is typically hard to shake the first-instance ruling. Even so, results vary by case, so a separate review at the appeal stage is needed.

If you would like to see how the materials in your case might be aligned, you can apply through starting a chat consultation now.

This article is general legal information based on the YouTube commentary above by attorney Shin Mijin of Jonjae Law Firm.

Reviewing attorney: Shin Mijin / Last reviewed: 2026-05-30

Disclaimer: This article provides general legal information and is not legal advice for a specific case. Outcomes can vary with the facts and evidence even in similar matters, so please consult an attorney for an individual review of any actual dispute.