Therapist Aaron T. Beck noticed that many couples have a tendency to notice only what is wrong. Couples in this situation often need help to consciously fight this tendency. So, he advises couples to keep “marriage diaries,” chronicling the things their mates do that please them.
"In his book Love Is Never Enough, he describes a couple, Karen and Ted, who kept such a diary. One week, Karen noted several things that she appreciated about Ted: He sympathized with me about some bad behavior by one of my clients. He pitched in to help clean up the house. He kept me company while I was doing laundry. He suggested we go for a walk, which I enjoyed.
Beck said, “Although Ted had done similar things for Karen in the past, they had been erased from her memory because of her negative view of Ted.” The same effect held true for Ted’s memory of the nice things Karen had done.
Beck cites a research study by Mark Kane Goldstein, who found that 70% of couples who kept this kind of marriage diary reported an improvement in their relationship. “All that had changed was their awareness of what was going on,” Beck wrote. “Before keeping track, they had underestimated the pleasures of their marriage.”
Source: Heath, Chip; Heath, Dan (2013-03-26). Decisive: How to Make Better Choices in Life and Work (Kindle Locations 1673-1682). Crown Publishing Group. Kindle Edition.