Things that inspire bad feelings or bad moods cause very long lasting imprints on the brain. Focusing on such things can inspire lasting damage in 30 seconds or so. However, things that inspire good feelings and moods require constant effort in focusing on the positives - they do not imprint the brain the way negative events do. So, if your spouse doesn't take an active role in constantly reassuring themselves of your good qualities and they associate bad feelings with you (it doesn't have to be something that occurs or occurred in reality, they could even imagine the slight) your fault will always be far more a part of their reality than positive contributions (even those exponentially larger than the percieved fault). This is physiologically true. To thrive in a relationship, we are required to maintain our positive emotive state towards our spouse through discipline and our spouse must do the same for us. This requires a fairly advanced level of self awareness to regulate and manage your own mood. It's quite apparent that the passively involved state of being that the cheating spouse is in where feelings happen to them (rather than being responses to thoughts that they can control as well as real events) makes it difficult to imagine them making the leap to the level of self control and responsibility required to be a good spouse.
When you talk about things lacking, that implies there was a kernal of whatever is seen to be lacking there. If the focus is on that which IS there - it's seen as a positive - then good feelings emerge. Therefore, I implore you to maintain your focus on the positive - appreciate things about your spouse. Regulate your feelings for them through your thoughts. If you recognize that you have had a negative thought, offset that with 5 positive thoughts. Appreciate them. Lead by example.
“No problem can be solved from the same level of consciousness that created it. ” – Albert Einstein
