I recently came off a longish self-imposed retreat and am happy to see some movement on the boards.
In my experience thus far, self-deception arises by a combination of past conditioning and a lack of mindfulness - often chosen. The habit of past conditioning (which I define primarily as childhood programming) has us always focusing our attention outside of our own sense doors. In other words, one hears a sound - that is a knock on the sense door - then the past conditioning kicks in to say, "That was a cat, yowling." then because we are SO used to allowing things that appear outside of ourselves to drawn us further from true understanding, we continue with, "I guess it must be in heat." So then we believe that thought and now, when someone comes to us and tells us the cat is sick, we defend our belief that the cat isn't sick rather than allowing for the possibility that it just MAY be sick...possibly to the detriment of the cat. I'm sure you could've come up with a better example. :-)
Mindfulness shifts our understanding of our thoughts and beliefs into more of a mode of "Guilty until proven innocent." I once heard a woman quoted as having said, "My mind is a dangerous place, I never go there by myself." It doesn't have much to do with the subject but I enjoyed the quote. But to twist it up so it can be useful here, if we consider all our thoughts and beliefs to be just another passing fancy, then it can be realized that they ARE just passing fancies. They are shapes in smoke, fun to watch but nothing to hold onto. But, if one doesn't watch them, then one runs the risk of falling into habit and believing them to be true, which may work out in the short run but will cause trouble in the long run.
One of the methods that helps me is this: I have spent many years meditating, studying, and living the Dharma to learn about who I am and what it's all about. A few realizations and understandings have presented themselves over the years, and yet I am STILL finding that I learn stuff. ("Wait! You mean I DON'T know it all???!!!" HA!) Realizations still happen. Now, I've arranged my life to allow me to have the time to study and meditate and have time alone and go for walks and listen to dharma talks and so on...most people haven't. With all the stuff I found myself filled up with, chances are good that others got filled up by a bunch of the same crap I did, yet they haven't had the chance to work on it as I have. Yet even with this, I STILL learn from them. This keeps me humble and allows me to understand that though we all - well, maybe you don't - often fall into the trap of believing one of our thoughts or beliefs are true.
So says each thought and belief.
If my thoughts were to take human form, I wouldn't believe it if that being said the clear Summer sky was blue. My thoughts have lied to me so many times I can only see it as entertainment anymore. I may act as though this thought or that one is true, but only as a scientist tests a theory.
As for the ending of the relationship, I once heard a story:
A Master of one town once heard that the Master from another town had died and so sent one of his disciples to see how the students of the late Master were fairing. Upon arriving in the other town, the fellow was aghast when he beheld the students of the late Master celebrating and singing in the streets. He went back to his own Master with the report, expecting his guru to rush tot he town to save the sanity of those fellows. Imagine his surprise when the guru smiled and said simply, "They understand."
I hope this helps in some small way.