Choosing thoughts versus being delusional.

Is there ever a point in which thoughts are simply “delusional?” Here is an example I thought of:

Wife thinks husband is having an affair with co-worker. She consciously chooses a new thought though and decides they are just friends, no need to create a problem that isn’t ultimately true there etc.

Only to find out a month later he was in fact having an affair the entire time she originally suspected and her original thought was accurate for this circumstance. Wouldn’t you say her changing her thought was somewhat “delusional”? I hope this question makes sense, I might not be articulating it well. Thanks!