Infidelity · What signs mean and what they don't
The behavioural changes people notice, why none of them constitute proof, and the mistakes that turn a suspicion into a problem — including one that is a criminal offence in Spain.
Short answer The pattern people report most often is not a single dramatic discovery but a change in routine that does not resolve: unexplained absences, a phone that never leaves their hand, a shift in mood on particular days. Any one has an innocent explanation. What people notice is several at once.
Read that list honestly and you will notice something: every item describes a change in behaviour and none describes evidence. That distinction is the whole subject.
Short answer Because each has explanations that have nothing to do with infidelity — depression, work trouble, illness, financial stress, a private matter unrelated to you. Signs justify finding out. They do not establish anything, and acting on them as though they did causes damage that cannot be undone.
Investigations that begin with a certain client end in three ways, roughly evenly. Sometimes the suspicion is confirmed. Sometimes it is disproved, and the person who was sure discovers their partner was hiding a diagnosis, a debt, or a family situation they were ashamed of. And sometimes the picture is genuinely ambiguous.
This is worth sitting with, because a confrontation based on signs alone has a predictable shape: it is denied, the behaviour changes, and you are left with the same suspicion and less ability to resolve it. If you are going to find out, find out first.
Short answer Do not read their phone, messages or email. In Spain, accessing another person's private communications without consent is a criminal offence, and it applies within a marriage. It also destroys any evidential value the material might have had, and can expose you to prosecution.
This surprises people, and it is the single most common way someone damages their own position. Spanish law protects the privacy of communications between spouses as it does between anyone else. Installing tracking software, placing a device on their car, or logging into their accounts falls on the wrong side of the line — regardless of whose name is on the mortgage.
The practical consequence in a family matter is that material obtained this way is not simply excluded. It shifts the conversation from what your partner did to what you did, at exactly the moment you need the opposite.
Short answer Through observation in public space by a licensed detective, documented in a signed report. What a person does where they have no reasonable expectation of privacy can lawfully be recorded; what happens in their private communications cannot. That distinction is what separates usable evidence from a criminal offence.
In practice this means establishing where someone goes, who they meet, how long they stay and how often — recorded with dates, times and locations, by an operative who is not noticed. A single occasion proves little. A pattern established over time is a different thing entirely, which is why these cases are measured in days rather than hours.
The report is signed by the licensed detective and can be produced in proceedings, with the detective available to speak to it. Whether you ever use it that way is your decision. Many clients never do; they wanted to know, and knowing was the point.
If you need to know rather than suspect, the first conversation is confidential and costs nothing. We'll tell you honestly whether an investigation is likely to answer your question.
Request a confidential callbackPeople also ask
Does infidelity affect a divorce in Spain?
Spain has no-fault divorce, so infidelity in itself does not determine the outcome. Where it can matter is indirectly — in questions of maintenance, of assets spent on a third party, or of cohabitation with a new partner, which can affect a maintenance obligation. Ask a Spanish family lawyer about your own circumstances.
How long does an infidelity investigation take?
Long enough to establish a pattern rather than an incident — typically measured in days of observation spread across a period, not a single afternoon. We will tell you at the quoting stage what we think your case realistically needs.
Will they know they are being followed?
They should not, and if they do the investigation has failed. Discretion is not a courtesy here, it is the operational requirement — a subject who becomes aware changes their behaviour and the opportunity is gone.
What if I am wrong?
Then you will know that too, documented, and you will have found out without having accused anyone. A significant proportion of these investigations disprove the suspicion, and clients describe that outcome as worth the cost on its own.
Can you investigate a partner who is in Spain while I'm abroad?
Yes, and it is a common instruction. You deal with us in English from wherever you are; the fieldwork and the signed report are Spanish and licensed.
The service
Observation carried out lawfully in public space and recorded in a signed report by a licensed detective. Nothing is recorded on your side and nothing proceeds without your instruction.
This article is general information for an English-speaking reader, not legal advice. If you are finding this period difficult, speaking to a counsellor or your doctor is a reasonable step alongside establishing the facts.