Cheating at Work: Signs the Affair Is with a Colleague

People spend more time with colleagues than with their family, and work offers what a parallel relationship needs: daily proximity, closeness and a ready-made explanation for any absence. That is why the workplace is one of the settings that comes up most in the infidelity investigations we handle in Portugal. In this guide we explain the most recurring explanations — sudden overtime, business trips and a sudden interest in company events — how to tell real work from an alibi, and what you can legally do about the doubt.

Quick answer: what are the signs of cheating at work?

The most frequent signs of an affair with a colleague are: overtime that appears suddenly and doesn't show on the payslip, more frequent business trips, a new interest in company dinners and events that used to be avoided, a colleague's name that comes up too often or stops coming up, «work» messages at unusual hours and a different concern with appearance on office days. None of these signs proves infidelity: careers change and there are busier periods. What counts is the overall pattern, how long it lasts and the lack of verifiable explanations.

Why work is such a frequent setting

Three reasons keep recurring. Time: many shared hours, joint projects, lunches and travel. Closeness: people who work together share pressures that the partner at home doesn't see. And alibi: «I stayed to finish a report» is a sentence nobody questions. This does not mean that every work friendship is hiding something — the overwhelming majority are not.

The most recurring explanations

1. Sudden overtime

A working day that for years ended at 6 pm now runs late two or three times a week, with no promotion, no new project to speak of and no difference on the payslip. Notice the days: when the overtime always falls on the same days of the week, it stops looking unplanned.

2. More frequent business trips

Trips that didn't exist before, journeys extended by one more night, weekends «attached» to meetings. The details are scarce — the hotel, who is going, the programme — and during the trip the phone goes unanswered for longer than is reasonable.

3. A sudden interest in company dinners and events

Someone who always avoided the Christmas dinner, Friday drinks or colleagues' birthdays now never misses one — and, often, the events no longer include partners. It is one of the most revealing changes precisely because it goes against an old habit.

4. Training courses, conferences and team-building days

These are a variation on the trips: events out of town, with an overnight stay, frequent and poorly documented. A real course has a programme, a certificate and colleagues who also talk about it.

5. Out-of-hours meetings and «emergencies»

Weekend calls that mean leaving the house, a problem «only I can solve», working breakfasts that didn't exist before. On their own they are normal in many jobs; together with the signs below, they carry weight.

The signs around the colleague

6. A name that comes up too often — or disappears

For weeks, a colleague is mentioned in connection with everything: what they said, what they did, how capable they are. Then, overnight, the name stops being mentioned. The two phases, in that order, are a pattern we hear about often.

7. «Work» messages at odd hours

Conversations at night and at weekends that bring a smile, answered in another room, in an app that isn't the company's usual one. The phone is the most common sign in any suspicion, and we explain it in our guide on how to find out about cheating on WhatsApp — including why you should not go and read the messages.

8. A different effort on office days

New clothes, perfume, more time at the mirror — but only on certain days, or on the days of particular meetings. When working from home, the equivalent is a sudden wish to go into the office.

9. Work becomes a closed world

They stop telling you what goes on at work, avoid you coming to pick them up, and the colleagues you knew are no longer invited home. Keeping work and private life separate is legitimate; it is the abrupt change that deserves attention.

10. Payslips and expenses that don't add up

Overtime that is neither paid nor compensated, lunches and dinners paid out of their own pocket, travel expenses the company doesn't reimburse. Money is often the most objective trail. See the full set in the 10 silent signs of cheating.

How to tell real work from an alibi

Before drawing conclusions, answer four questions:

• Is it verifiable? Real work leaves a trail: emails, results, payslips, colleagues who talk about the same project.

• Is it consistent? The explanations hold when you repeat the question days later.

• Is it shared? Someone who is overloaded usually complains and gives details rather than hiding them.

• How do they react to simple questions? Tiredness leads to venting; an alibi leads to irritation.

To organise your answers, you can take the 7-question infidelity test.

What you should not do

When the affair is at work, mistakes have consequences that go beyond the relationship:

• Calling the company, the manager or colleagues. It exposes your private life, may harm your partner's professional standing and, if it involves accusations without proof, may have legal consequences for you.

• Turning up at the workplace to confront someone. It escalates the conflict and can be used against you.

• Accessing the work email, computer or phone. It may be a criminal offence in Portugal, even between spouses, and may also involve the company's confidential information.

• Exposing the colleague on social media or to third parties. Public accusations without proof may amount to defamation.

• Placing a GPS tracker on the car. If you suspect that you are the one being watched, see how to detect a GPS tracker on your car.

What to do when you suspect an affair at work

1. Record facts

Days and times of arrival, announced trips, events, expenses. After a few weeks, a pattern — or the lack of one — becomes visible.

2. Talk at a calm moment

Talk about what you have observed and the distance you feel, without accusing or naming names.

3. Find out about your rights

If marriage, children or assets are involved, a conversation with a lawyer helps you decide with confidence. We have put together a list of the best family law attorneys in Portugal.

If you are already thinking about divorce, see which proof of infidelity has legal value in Portugal.

4. Ask for professional confirmation

When the doubt persists, an infidelity investigation confirms or rules out the suspicion with facts.

How a private detective investigates an affair at work

Work-related cases have one advantage: they are predictable. There are leaving times, lunch breaks, fixed «overtime» days and scheduled trips. The investigation focuses on those moments and documents what happens in public places: the actual time the person leaves, where they go and with whom. A detective does not enter company premises, contact colleagues or access emails or phones.

The work begins with a free and confidential initial assessment and a fixed quote with no hidden costs — learn more about how much a private investigator costs in Portugal. To organise the fieldwork we normally need 24 hours' notice; for trips, the earlier we know the dates, the better. At the end you receive a written report with photographs and video. All investigations are coordinated by detective Alexandre Ribeiro, a member of WAD (no. 1687), APDPE (no. 1326), LIDEPPE (member no. 33) and IKD.

Frequently asked questions about cheating at work

What are the signs of an affair with a work colleague?

The most common are sudden overtime, more frequent business trips, a new interest in company dinners and events, a colleague's name that comes up too often or vanishes from conversation, and work messages at unusual hours.

How do I tell real overtime from an excuse?

Real work is verifiable and consistent: it shows on the payslip or in results, the explanations don't change from one telling to the next and the person doesn't get irritated by simple questions. An excuse tends to be vague, to vary and to leave no trace.

Can I call the company to check my partner's hours?

You should not. Besides exposing your private life and possibly harming your partner's professional standing, an accusation to third parties without proof may have legal consequences for you.

Should I confront the colleague?

No. A confrontation without facts may amount to defamation if it involves public accusations, it escalates the conflict and it makes both of them more careful.

Can a private detective watch someone at their workplace?

A detective does not enter company premises or contact colleagues. A detective documents what happens in public places: actual leaving times, lunches, journeys and meetings outside work.

Can business trips be investigated?

Yes, provided the investigation is planned in advance and carried out in public places. It can confirm whether the trip exists, where the person stays and who they are with.

Need to clear up a suspicion?

Talking to us is confidential and involves no commitment. We work throughout the country, including Lisbon, Porto and the Algarve. Call or send a WhatsApp message to +351 936 225 975, 24 hours a day, or learn more about our infidelity investigation service.