One of the many ways to encourage premarital couples to identify positives attributes in each other and also respond positively with optimism would be first to demonstrate to them how they could develop positive affirmations that would combat their own internal personal negative irrational thoughts and perceptions. When one learns to change the way he or she thinks and feel about his or herself in a positive outlook they can begin to build up/affirm their loved one’s esteem and identify their positive attributes.
I would admonish premarital couples to see Jesus in each other and understand that each is a child of God and a sister and brother in Christ in order to maintain some level of respect for each other. When you are self-confident you are able to esteem others. What I sometimes encounter during a counseling session is interacting with a client who can easily encourage and maintain optimism towards his/hers loved on but have difficulty doing the same for him/her.