I work with a lot of step families between the couples I see, the teens I work with, and the step family group I run. One of the things that has become apparent in all this work is that children are intuitive and pick up on the strength of the couple relationship and this impacts the functioning of the children and ultimately the happiness of the family as a whole. Children in a step family have already experienced the ending of one relationship or have experienced the effects of a single parent home. They have felt the pain and guilt associated with the absence of a parent and many children believe that they are partly or wholly responsible for their parent leaving, even in the case of death. Due to this, they are more likely to test the step parent to make sure that they will be sticking around before they allow themselves to get too close and to really rely on their step parent.
The difficult thing about this is that many step parents believe that their step children should automatically respect them and they are also hoping for them to like and be nice to them. The aforementioned hesitancy of step children to get close to their step parents and the testing of the boundaries behaviorally looks quite opposite to what step parents are hoping for. This could cause a negative cycle in which step parents show children behaviors that they read as not being there for them and not being in the relationship for the long haul.
So what can the couple do? Well, it is important for the couple relationship to be strong to uphold all of the stress that comes with the step family situation. In addition, as the children pick up on how solid the couple relationship is, they will intuitively learn that they can rely on the parents more. This may take longer depending on the number of relationships the children have seen end around them. This is also important for the children as they learn how to fight fairly, disagree, and get along with others in general. Children learn what to expect in a relationship from the parental relationships around them which sets up the foundation for the type of relationships they will get into when they are older.
Overall, the strength of any couple within a family is the foundation for the rest of the family. Your step family has the possibility to be as strong as your couple relationship is. Although many of the typical concepts for strengthening a relationship apply, in addition you will need to work more on compromise, understanding, and appreciation.