When a relationship has lots of good in it, but the karma that brought two people together has been worked out, one or both are not always willing to listen to their intuition. Pain is then inevitable.
We can all have the tendency to hold on because we are addicted to what was or is still there in the relationship. We may feel we may never get that good stuff anywhere else.
If a relationship is meant to continue, both partners will remain committed to it, even in the face of difficulties. But if one or both are resisting the undercurrent that is trying to take them on to a new experience, then both are out of the flow of life.
The extent to which the subtle imprints in our astral selves, is trying get us to move can be seen through wise interpretation of astrology. In our behaviour, we will feel the distance growing in the relationship. How much we pay attention to the signs is determined by how strongly our ego has us in its grip. If we can be aware or 'conscious' of intuition, listen to it then the way forward will be clearer.
In a relationship where there is a big a gap between how conscious you are and your partner is, there cannot be the depth of communication needed to transcend the root causes of problems.
In this case you have to decide if you are willing to continue, or if it is better to move on and create space for a more compatible relationship to manifest.