You Have A Gut Feeling That They Are Cheating
Sometimes there are no outward signs that you detect but you sense that something strange is going on. In some cases, you might be over-jealous but in other cases, your gut might be telling you something.
Try and figure out what the reason is for that feeling and if you notice some of the signs that were mentioned here as that could be an indicator that your partner is cheating on you. There are countless cases where someone just had a gut feeling that their partner was cheating on them and it proved to be true.
So never ignore what your intuition is trying to tell you. People are very complex beings and your intuition is what some consider the sixth sense, something that is much more powerful than your other senses.