According to John Gottman's research, two thirds of problems in relationships, including happy relationships, are problems that never get resolved.  We generally have a media-influenced idea that the right relationship will only have problems that are resolvable.  The difference between a happy relationship and an unhappy one is how the couple relates to the perpetual problems.

In happy relationships, couples raise the problems frequently; they don't shove them under the rug.  But when they raise them, they handle them with good will and respect toward one another. Sometimes humor helps, as do small compromises that don't change the core of the problem, but take the edges off the differences. For most people, this is very challenging, and is the key to how we need to grow through the opportunity of being in a relationship.  Gottman also found that in happy relationships there are five positive interactions for every negative one.  That is five compliments, appreciations, thank you's and so on for every criticism.  With fewer positive for each negative, or even an even amout of each, couples generally self-destructed.  In a way, this is so simple, yet few people do it, or even think of doing it.