Why do have doubts about your wife? Do you have proof about her infedility? Do not suspect your wife on your assumptions. Suspicion in married life can destroy your relationship. Your mental peace disappears. Ask your wife directly about your doubts. But be very reasonable. If you are wrong she is going to hate you. Confirm your doubts.
If your wife knows that you are suspicious of her, she will no doubt be extra vigilant and careful to cover her tracks. One thing is certain, things like that will come out in the end, sooner or later. Perhaps your main aim should not be to “catch your wife red-handed” but rather to try and keep your attitude and your behavior right towards her, to treat her with dignity and respect, so that when and if you do discover that she has been unfaithful to you, then she will feel convicted that she has done you wrong. Keep your eyes and ears open, be wise and careful, and remember your wife is a human being just like you.
Catching your spouse “red handed,” so to speak may not be necessary. Consider what you would gain by achieving this purpose and compare that with what you would lose. Have you confronted your wife with your doubts of her fidelity? If not, discussing it openly as a relationship issue might be advisable. You’ll need to realize, too, that going behind her back to tail her or secretly have her photographed would be breaking her trust, which makes you the bad guy in this scenario. She’ll have every right to be just as angry at you for violating her privacy as you are with her over suspected marital infidelity.
I wouldn’t advise spying on your wife, but if you are determined to find out for certain whether or not she is having an affair, I can make some suggestions. Is there a change in their behaviour or appearance? They may be trying to look more attractive for their lover. Changes in habits or sleeping patterns can also be a warning sign. Drop by unexpectedly if you want to find them together. You could check their recycling bins for papers or their phones for text messages or numbers you don’t recognise that they speak to often. Follow them after a fight as the may be using it as an excuse to leave the house. If they change the passwords on their social media accounts it should raise a red flag in your mind.