Suspicions of infidelity can arise when your mate's mobile phone rings in the middle of the night.
It was most likely a wrong number, but you can't get the idea out of your head that it might be "someone else".
If you've been feeling suspicious about your partner, you need to take a good look at your relationship.
If your mate spends hours on the computer and takes their phone everywhere (even into the bathroom), or if your partner isn't as demonstrative or communicative as before, you may be wondering if someone else is in the picture.
If things aren't going great in your relationship, you may find yourself looking for the reasons why. If the spark has faded, and neither of you is doing anything about it, you may very well wonder how your mate is dealing with this dry spell.
A lack of sex in your primary relationship, though very common, can make you question the trust.
One of the best things you can do in a situation like this is to talk about it with your partner. You need to ask those tough questions and admit to your insecurity.
Try to get on the same page with your partner so the two of you can reassure each other.
Unfortunately, if the one you share your bed with is unwilling to have this conversation, it will only give rise to greater suspicion. At that point, you may need to discuss things with a counsellor.
If you're married, and your partner is unwilling to work on the relationship with you, they should consider that the next person you may talk with could be a lawyer.
You are both better off having the conversation, no matter how difficult.
If you have reasons for your suspicions, you need to give your mate a chance to explain and come clean if they have strayed.
Infidelity does not necessarily mean the end of your relationship, but it does mean that some serious work needs to be done.
People cheat for different reasons. They may love their partners at the time.
Sex, addiction, personal insecurity and payback are just some of the reasons both men and women have extramarital affairs. None of them are good, but understanding why can help.
If you want to keep the relationship, remember that it all starts with communication.
Of course, infidelity is a scary subject to bring up, and it all may be coming from your imagination. Please get clarity before you go any further in your doubts.
If you find out that your mate is playing around, get serious, tell them how you feel and make an appointment with a qualified therapist.
There can be a lot of life left in your relationship. Go find it.
* Dr Barton Goldsmith is a psychotherapist and author.