Why these three?
In Korean saju, your Day Master is the heavenly stem of the day you were born, and it works like a personality type. Three of the ten souls have an especially hard time sitting with an unfinished conversation. Jeong Fire, the candle, needs emotional closure; an open loop feels like a draft in the room, and the urge to fix it is physical. Sin Metal, the jewel, replays what went wrong in high definition and wants to correct the record, politely, at 1:14 a.m. Gye Water, the rain, feels everything a little late and all at once, so the text arrives weeks after the breakup, just when everyone assumed the chapter had closed.
What saju can and cannot tell you
Saju can describe your habits: how you attach, what you do when you feel unfinished, which kind of silence you find unbearable. It cannot read anyone else's heart, and it cannot tell you whether a relationship will restart. Nobody honest can. What it can do is help you notice the moment you are about to act on a pattern instead of a decision. That pause is the whole point.
A better question than "should I?"
Ask what you want the text to do. If the answer is "make me feel better tonight", write it in your notes app and wait until morning. If it is a real apology or a real question you are ready to hear any answer to, that is a different message, and you will write it better after sleep. Candles, jewels and rain all make clearer choices in daylight.
The other seven souls
Not a Jeong, Sin or Gye? You have your own pattern. Gap Wood goes silent and calls it dignity. Byeong Fire posts a glowing photo instead of texting. Mu Earth waits for the other person to move first, for years if necessary. Find your soul to see yours, written by Bom, who will be kind about it, and Yeon, who will not.