You do not have a soul mate. I do not have a soul mate. Or, rather I should say, whether or not we have a soul mate or we have chosen to build a life with "the One" plays absolutely no part in cultivating a healthy relationship and a successful marriage.
In fact, the belief that there is a soul mate is a crippling disadvantage. It means your relationships are primarily driven by fear. You’re afraid to commit because perhaps this girl isn’t "the One". You’re afraid to leave because perhaps this one is. Always fear.
This kind of fear leads to indecision and to a more frivolous view of marriage. A marriage is not eternal and it is not work. A marriage is a commitment not to another human being with all the flaws and deficiencies that you have—and more!—but to an ideal that you created and to which you demand another person conforms. The idea of a soul mate is a belief in fate, but not a patience for it. You’ve already generated your ideal, and now you are working to make anyone who crosses your path, however suitable, conform to it.
And as we know from Marcus Aurelius, trying to change other people is a losing game. You are only guaranteed the ability to change your own mind.
You believe in the soul mate, you create an impossible ideal, and you set out to make a girl into that ideal. You amplify her virtues and sweep her vices under the rug, never to be seen. Or else you wrap them up in some theory that allows them to look like virtues, too. And when you finally succumb to that truth that she will never live up to whatever this ideal is, then you’ll pretend that marriage is about happiness and this one can’t be "the One" because she’s not doing everything exactly as you like, so you move on. You divorce, you find another girl to work on and to lie to yourself about.
There’s nothing romantic about the soul mate myth. It’s selfishness and it’s weakness and it’s laziness.
Tolkien knew as much. In a letter to his son, he wrote this:
[The centre of the romantic chivalric tradition] was not God, but imaginary Deities, Love and the Lady. It still tends to make the Lady a kind of guiding star or divinity—of the old-fashioned ‘his divinity’ = the woman he loves—the object or reason of noble conduct. This is, of course, false and at best make-believe. The woman is another fallen human-being with a soul in peril…
It takes, or at any rate has in the past taken, the young man’s eye off women as they are, as companions in the shipwreck not guiding stars.
Companions in the shipwreck. No soul mate. No "the One". A marriage isn’t a corny enjoining of perfect beings into all-happiness with one another for all eternity. It’s a commitment to struggling together, to never giving up on that struggle for the sake of one another, to working toward elevating ourselves so that when our ship comes we’ll have become well-suited to make our escape—together.
The idea of a soul mate comes with idolatry—this marriage will save me—while the truth is something else:
God will save us through this marriage.
It’s work. It’s always work. It’s supposed to be work in this fallen world, and there’s nothing to fear when you both have skin in the game.
There is no "One". There’s only us.