This is a purification and death process unlike anything most people could ever anticipate.
Harmonious Twin Flame Union is not just a psychologically balanced relationship between Twin Flames. It's kind of like attaining Mantra Siddhi of the One Devi. In some Western traditions, it's kind of like attaining Knowledge and Conversation of the Holy Guardian Angel. (There are no exact equivalences though - these are all ultimately separate paths.)
What's essentially happening is a very high frequency dissolution of the illusion of separation - while, at the same time, grounded individuation in the human form. It has nothing to do with your Twin Flame, although my Twin and I are slowly re-uniting. But it still has NOTHING TO DO WITH THE PHYSICAL TWIN FLAME.
This entire process has nothing to do with wanting your Twin, it has nothing to do with anything of that sort. This is driven by one motive: you want your soul and you want God. You know you cannot live without God/Love.
And there no way to avoid facing the utter darkness that stands between you and God. There is no romanticism here, no high ideals, even though this is the path to the highest ideal of them all with the greatest Lover of them all.
This is a dangerous ego death with no external savior to help you. The safety is off, the training wheels are gone, and you will face the full malevolence of the "Matrix" as you fight to leave it.
Nobody wants to talk openly about what really fucking happens on this path to Harmonious Twin Flame Union, so I will give a glimpse of what can happen.
You will be attacked by abusive spirits who want to siphon your energy, cage you and imprison you, feed off of you, and destroy you. You will uncover demonic possessions inside yourself and inside your Twin Flame. You will know the horror of seeing your otherworldly Twin Flame love being eaten - yes, eaten - by parasitic spirits. You will experience betrayal and abandonment on levels that cannot be believed. You will uncover dark truths about humanity that cannot be believed. You will uncover dark truths about the False "God" that cannot be believed. You will experience murder attempts (yes, I have experienced murder attempts - to the point where I am barely even surprised anymore). Torture. Death. The most skillfully orchestrated sabotage and destruction imaginable, almost as if your life is a plot.
You and your Twin will play out archetypal themes from mythology and religion, and I don't mean that in a psychological sense. You and your Twin will actually, literally, for real REAL play out archetypal themes from mythology and religion.
And sometimes the Light is more terrifying than the Evil. Back when I still had a Sri Yantra on my altar, there was one night when Anandamayi Ma appeared in the Sri Yantra. She emanated such a bright, pure Light that I squeezed my eyes shut in terror. It felt unsafe to look at such Light. Her sweet voice was the exact same voice I had once heard the night before my initiation into Sri Vidya - the voice of Tripura Sundari.
It filled me with fear.
Since then, my Twin Flame and I have had to battle very dark spirits. Murderous fae, predatory hungry ghosts, imposter spirits, curses and false gods. Shocking evil in human beings. Everything that is Not Love.
You are not ready for it. There is no way to be "ready" for it and there is no skill set or spiritual mastery that can minimize these risks or make the torture and horror go away.
If you really want Harmonious Union, prepare to have everything inside you and outside you get burned down in savage, unforgiving, politically incorrect ways that don't match the glib "teachings" of candy cane spirituality and the so-called benevolence of the universe. Prepare for upheaval that doesn't match the dogmatic, diluted, distorted and policed teachings about Kundalini awakening.
This is a free fall into the abyss.
This is Judgment.
This is the death in life before your physical death.