How can I maintain an optimistic relationship with my wife?

A lifetime's joy. Trust her. Be a little bit blind to her faults. Don't try to understand her or make her understand you. Listen. Relationships are more important than being right. Find something that you can both reasonably believe in and that serves others and share this activity. Do what you can to make her happy. Honor her in front of others. Make her feel loved, safe, protected, adored.