this is a very interesting point you have made. my ex-T also lied about things and for me it definilty diminished the level of trust that i had with him. eventually, because i knew he was not always truthful or forthcoming with me, similar to what you said, i no longer felt guilty or particularly obligated to be as honest with him in return. i suspect much of this came down because of the power struggle that was unfolding in the relationship.