Marriage loyalty lasts only four years, attraction to the opposite sex is just a chemical reaction - Psychology - Psychology Express

The "attachment" in love usually lasts for four years stably, but it is not a justifiable reason for extramarital affairs, nor does it mean everyone will experience a change of heart as a result, because love is still subject to many factors such as morality, ethics, society, and culture. However, understanding this physiological mechanism in humans might give us a new feeling or gain when we approach love and marriage. -psytopic.com