In the strictest sense, marriage is a contract between two people and the government. A couple can choose to present their relationship to society at large in this form, accepting corresponding legal duties and benefits.
The main source of stress in marriage is that although the law defines marriage legally (between the couple and society), it does not define the relationship between the people getting married. People come to see marriage as others practice it, they copy the relationship forms and enter marriage with a set of unclear expectations.
The way to overcome difficulties is through communication, communication and communication. Although the process of communication may bring to the surface some of the problems and cause stress this way, not communicating causes even more stress and makes problems unsolvable.
Every person is different and every relationship is more so different. Having a clear head, an open heart, and willingness for sincere, non-judgmental communication is a good start for achieving a deep, balanced and meaningful marriage.