I mentioned elsewhere that I dislike mathematical expressions for the Trinity because math is inherently limited when it comes to God. But this isn’t too bad. I’d sayMarriage is the “primordial sacrament” of the inner life of God.
One loving the other loving the other, the love is a third reality.
Married couples speak about “our love”.
Truly, 1+1=3 in God’s economy.
1+1=1=3.
That makes no sense mathematically, but it’s the best we can probably come up with for the processions.