If trust is the most important in a relationship, and you feel an instinct that your boyfriend is lying to you, how would you tell him how you feel without accusing him, or worse let him accuse you of distrust then dumping you? You would have to be willing to study the signs, and then make a decision.

Observe the eyes, the windows to the soul. If he looks at you less, and is consistently looking away, that could be a good sign that he is not being honest. But you have to question yourself if you remembered if this is the way he usually behaves or is there inconsistency from the past.

Look for nervous behaviors. Most people are nervous when they lie, and this can be told from their eyes, their hands, their legs. Do you observe nervous behaviors that he did not exhibit before? Are his hand movements odd? This is sign number 2. He may also seem to defend himself in any conversation. This is a subconscious act if he is trying to hide something from you. So the more defensive he seems, the more likely he is lying. Note if he regularly tries to change the subject of discussion. Lying is not a comfortable thing for most people so he will try to change the subject; the longer the lying the more uncomfortable he feels. If it is a subject that he does not require to lie, then he would be most comfortable sticking to that subject.

This is not exhaustive list of things to look out for. Remember that dishonesty will leak at some point, if he does not confess. If you feel a really strong hunch that he is lying, then speculate no more, hire a private investigator to find out. That way, if he is lying, you can do something about it sooner. And if he is not, and then you can rest your weary heart.