A recent Journal of Personality and Social Psychology says we are biased to be generous in evaluating people we are intimate with, especially for mating-related traits, and are more biased for happier relationships. We are also aware that we and others are biased in these ways:
Meta-awareness of bias in intimate partner judgments was investigated in 3 studies. In Study 1, participants rated fictional partners in happier relationships as more positively biased in their partner perceptions. In Study 2, participants thought their judgments of their own current partners were positively biased and that they were judged by their partners in a positively biased fashion. Using a sample of couples, Study 3 showed that metaperceptions of bias were anchored to actual levels of bias at the individual and relationship levels. In addition, positive bias was accentuated for traits that were more relevant to mate evaluation. These findings (as expected) suggest that positive bias in partner judgments can be a normative and consciously accessible feature of intimate relationships.
This is a clear example that being aware of our biases is not enough to eliminate them.