The obstacle shows up as constant checking. The person compares words against times, notices discrepancies, verifies what was said — and usually finds confirmation of their suspicions where there is none.
This destroys a relationship faster than the thing they are afraid of.
What it blocks is sensitivity. Behind this point is someone with a fine feel for people and their states; but a sensitivity aimed at hunting for deception stops working towards understanding.
What to do: ask directly instead of investigating. And accept the answer for as long as there are no real grounds not to.
