From the Catholic Online article citing St. Thomas Aquinas:
The first duty which is incumbent on man is to give up sin and resist concupiscence, which are opposed tocharity(sic) ; this belongs to beginners, in whose hearts charity is to be nursed and cherished lest it be corrupted. The second duty ofman(sic) is to apply his energies chiefly to advance in virtue ; this belongs to those who are making progress and who are principally concerned that charity may be increased and strengthened in them. The third endeavor and pursuit of man should be to rest in God and enjoy Him; and this belongs to the perfect who desire to be dissolved and to be with Christ.
The Purgative, Illuminative, and Unitive ways have traditionally applied to our spiritual life. That is, our journey in relationship with God.
Now, let us have a look at our own marriage and how that journey can be seen through the same set of lenses.
The first state is that of the beginner. By purgative, I am called to purge all that is within me that holds me back from giving myself completely and totally to Lucille.
I am called to learn how to lay my life down completely for Lucille and when the time came our children. Just as Jesus did and does for His Church.
That means purging my attachment to things, to places I visit in person and virtually that take me away from Lucille, and to any outside spiritual influence that is not of God.
This is a tough one. It is really difficult to let go of the toys, of my wants and desires, and in some cases my dreams that I am discovering may never be fulfilled.
Where my treasure is, so is my heart (Matt. 6:21). I want my treasure to be my wife and my family founded in Jesus Christ and His Sacrament of Marriage.
After a number of years into our relationship, I have discovered in myself a good view of my weaknesses and propensity to commit sin that impacts my marriage.
But, in the process of discovering and purging the things that were holding me back in my relationship with Lucille, I have begun to discover things in her I could not see before because of those things that held me back!
Forgiveness plays a huge part in the discovery, or Illumination of our marriage's gifts and glories. As we develop a communication method that incorporates the ability to express ourselves without fearing a destructive criticism death spiral, forgiveness enables us to look past it all and begin to discover those gifts and glories.
The Illumination of Lucille's heart, and my ability to "see" into it is also a beautiful benefit of letting go. The more that I let go, the more beautiful she becomes. The more that I let go, the more I can embrace Lucille in all aspects of our marriage and being.
The other side of that coin, and one that is critical for the deepening of our marital relationship, is the opening of my heart to Lucille.
The Illuminative process is a two way street of the heart. One outbound to Lucile's heart and one road inbound for her to take up residence in mine.
This state is a bit tougher to address at this point for me.
Because our marriage is only 7 years young.
We have been blessed though to catch glimpses here and there into the truly amazing gift that God gives us in our Marital Unitive state.
One that we both have experienced is the union of our two hearts founded in His Blood. There is very neat Joy that begins to find residence in both of us as we become more and more open of heart to each other.
That Joy is somehow founded in the realization that Lucille loves and accepts me as I am and that if things go sideways on us we have an established mechanism to work on forgiveness and penance.
Some further reading:
Feast of Pope Saint Gregory the Great