When you find the "right one", ur soulmate ... does the fear of making a mistake go away?

Nope, that fear never goes away. There is no way to totally make it go away, although making a commitment does help. Believe it or not, sworn word does mean something to many people. But even when you make a commitment, and even when that commitment does mean something to both of you, you can count on it that you will both still sin. And one or both of you may sin badly enough that it will break up the marriage, if the other can't forgive it (which is also a sin).

But the bottom line is, whether or not it turns out to be a mistake, you have two choices: either you suck it up and take the plunge or you stay forever on the side of the pool. If you stay forever on the side of the pool, you can count on it that you will miss out on wedded bliss. You can count on it that you have made a mistake. Its like when you are taking a test in school and you are facing four answers and you aren't sure which on is right. If you don't answer it, you have for sure gotten the answer wrong and you for sure get a zero on that question. Do that to enough questions and you've failed the test. But if you guess on it, you have a 25% chance of getting it right. If you can eliminate two of the answers because they are ridiculous and guess between the final two, you've got a fifty/fifty chance of getting it right. That is a whole lot better odds than a certain zero.

Refusing to get married because you can't eliminate all fear of making a mistake is a certain zero. Make enough of those mistakes and you fail the test of life. If you at least give it a shot, you have a chance at a relationship that will improve you as a human being. It will make you stronger, braver, tougher, more loving, more vulnerable (dichotomies are a bi***, aren't they?) and more broken. It will sweeten life immeasurably. You can count on your spouse being imperfect. You can count on yourself being imperfect. You will be unhappy sometimes. You will have joy sometimes. If you stick it out, you'll reach contentment. It will be unequal. There will be times when you fall and he picks you up. There will be times when he falls and you pick him up. He will work long hours, you'll do more housework. Its just life. But marriage makes life so much more important, so much more expansive, takes you so much outside of yourself and is worth more than you have to give it.