Assurance comes from Old Latin, to secure, to make safe. I believe it's a natural human desire to assure the ones we love, to make them feel safe, and it can seem counterintuitive to put a limit on re-assuring someone who has lots of anxiety and suffers from OCD. Assurance evokes the hymn Blessed Assurance, by Fannie Crosby and Phoebe Knapp (note, if you click on the song, it starts playing)which I remember singing in Sunday School, and loving the feeling of certainty, the exuberance of knowing something for sure.
I used to try and figure out the difference between "assurance" and "reassurance"--was I seeking information that I really needed, or was I doing a compulsion to lower my anxiety briefly, before researching again and again. I finally accepted that I can't definitively know this, that OCD is crafty in coming up with ways to bluff and say "You really need this information. You really need to search. This is new." My longing to definitively figure everything out is part of the disorder of OCD. Yes, uncertainty is painful for human beings, even without OCD, but OCD tells the lie that you can think your way through using compulsions. Reassurance doesn't last. Reassurance is a false sense of safety and security.Blessed assurance, Jesus is mine!
O what a foretaste of glory divine!
Heir of salvation, purchase of God,
born of his Spirit, washed in his blood.
Refrain: This is my story, this is my song,
praising my Savior all the day long;
this is my story, this is my song,
praising my Savior all the day long.