OH Fuzzy-- this is an excellent question-- IMO!
and one in which I think the answer or answers can be confusing.
I used to think the way I saw things as happening was the "truth" and "reality".... but lately, I'm realizing that it's only MY truth and MY reality. I think we can try to grasp and understand anothers reality-- but that's only if we try....
Like here's an example-- hope it's OK ....
When my boys were really little, toddler/preschool age, my husband worked 12-14 hour days at least five sometimes six days a week..... our youngest didn't even know him-- and to this day remembers thinking some man came to visit on Sundays--

anyway-- my reality at the time was that I was worn out taking care of kids 24/7 and NEVER getting a day off when my husband got Sundays off of his work.

I thought he didn't care about us as a family-- that was MY reality. His, now that we've talked about it years later-- his reality was that he had to work that hard to provide for us (yes, his reality was skewed, for one didn't have to work that MUCH--but it was his reality nonetheless)
He couldn't understand why I was upset at him for working so hard and I couldn't understand why he couldn't be home with us as a family and perhaps give me a time-off from dirty diapers, runny noses, spaghetti-o's and singing "twinkle twinkle little star"-- 30 times a day--

...
Now, looking back I know his reality... but I had to try and understand and know where he was coming from......
I think without trying and truly knowing the other person's motives one can't know the other's reality..... does that make sense??
I think it's very insightful of you to ask this question.
Fuzzy---
mandy