This is a grave error! There are constantly new challenges in marriage. Just keeping it fresh, lively and exciting is a challenge. Plus, life [i.e. Hashem] is always sending difficulties and new opportunities for growth to make life interesting. The quality of your relationship with your spouse upon the birth of a child or a career change is something to get your juices flowing. Also, over time there is built up anger and tension. Dealing with this and maintaining love and harmony are areas where one should feel he still must work to achieve success.
With blessings for love and harmony - I remain faithfully yours...
Ba'al Hamevakesh - E.B.H.M.
Shavua Tov:):)