The obvious connection to the psychological trait of Observing Ego skill is here, in mindfulness as a virtue, a character trait, and a mature ego defense. It is coming from a present moment perspective in time, a capacity for curiosity, and acceptance of the reality that we all have growing to do. It is nearly identical to Observing Ego in these features.
When we consider those aspects of being in any long term commitment, that there is imbalance that we can correct back to balance, the ebb and flow of power within the couple, the times of trouble in which, “This too, shall pass,” and the times of happiness which will surely fade a bit before returning cyclically back to happiness - the “watcher” of our own story, being witness to the life of our beloved partner, and the ability to be the narrator of our own life and of our relationship is essential to retain perspective that we will need in strategically charting our course to any lifetime goals as individuals and as a couple.
This virtue, this mature defense mechanism, built of Observing Ego, will be sorely needed.
If you have ever been with an uncurious person, or someone who only lives in the moment and without perspective on there being a shared past in which we invested in each other, or a future that we have the power to chart a course to, then you know the great loneliness of love in a relationship that cannot be what you need.
Seek a mindful person as a partner.