Our minds aren't perfect at remembering special details and specific facts - far from it. Our brains work selectively; they store and recall certain bits of information while forgetting others. For example, you might remember - for whatever reason - a phone number that has little or no importance to you, but forget the birthday of someone you really should buy a present for.

On the most part, this selective/subjective memory trait creates no real problems in our day to day lives. We can look up a number if we forget it, or ask a friend of a friend for the day of the month on which someone's birthday falls.

However, sometimes it can make things slightly trickier. One such time is when we suspect our partner may be cheating on us. Imagine you walk into the room just as your partner is putting down the phone and they seem a little on edge or tense as they turn around and see you. The incident may stick out in your mind for weeks, niggling at you, making you wonder: did it mean something, was it a sign?

Fast forward to a different occasion, when your partner returns home from a business meeting or other engagement late and immediately jumps in the shower, even before properly saying "hi" to you. You might rationalise their behaviour by thinking: "Well, they were probably tired or something. They surely just felt like refreshing themselves with a shower," then forget all about it. You might be 100% right, but that's not really the point.

The strange phone incident and the unusual dash to the bathroom on returning home could both have happened because your partner is cheating on you, and conversely they both could be wholly innocent and not caused by infidelity. The point here is, remembering one incident over the other and thus giving it more weight or meaning than the other in your mind could potentially make it much more difficult to ascertain what is or isn't going on - whether they're trustworthy or not.

So, to combat the human tendency to selectively remember and therefore consider some incidents more than others, and therefore improve your chances of revealing the truth, you should keep an objective, non-selective record of everything that happens. Here's how it works:

1. Use a journal or diary, not a digital method of recording events, changes in behaviour/habits/moods, etc. Noting things in your own handwriting allows each piece of information recorded to be absorbed more deeply and permanently by your mind than if you type them out quickly on a computer. Also, paper records (a diary, journal, etc.) are usually more portable than laptops, PC's, etc., which could come in handy if/when you spot a potential sign of infidelity away from home.

2. Keep your journal as objective and neutral as humanly possible. Note the time something unusual, strange or suspicious occurs, if you've noticed it before, and what it consists of. For example, saying: "Today (insert date) they came home 2 hours later than usual from work, it's happened once before and they offered no reason or explanation for their lateness" is much better and more useful in the long run than: "They came home late again! They had no reason to be late at all. It must mean something."

So, be specific, neutral, accurate and non-judgemental. A time will come when you'll make a decision on whether or not you can trust them and it'll be then when an emotional response will be completely warranted and understandable. Until then, record what happens like a robot - it'll help unravel the mystery and reveal what the hell is or isn't going on.

3. Finally, keep your journal/record hidden away somewhere where it won't be stumbled upon by your partner. If they ARE cheating and find your diary, it could easily make them more secretive and more careful not to give out noticeable signs of their infidelity in the future - thus making your job of uncovering the truth more difficult.

If they find it and are NOT cheating, they could feel insulted or hurt that you don't fully trust them. That's an issue that, if appropriate, can be brought up by you after you've completed your little "investigation". For now, secretiveness is quite possibly one of your greatest allies in discovering whether or not your partner's having an affair.