FU to "How Do I Trust Again?"

In regard to another Scholar’s prior question, the response indicated the fact was that the Scholar’s husband talked to another woman at the beginning of their relationship and had not done so since. However, we can’t really know if he has done so since, correct? It seems to me the statement regarding his subsequent actions is not definitely a fact.  Can you clarify further how to approach the anxiety/ doubt issue if the latter part of the statement is not assumed to be a fact? Many thanks!