Dear Rachel,
Is there any guarantee that each person will meet his or her soulmate and will find someone who truly loves them? Time and again I have had my heart broken and my hopes dashed. I'm considered attractive, I'm kind, generous, sensitive, smart, intelligent, warm, and fun to be with. So is there really someone out there for everyone?
B.D.
Seattle, WA
Dear B.D.,
It is said that before each of us was created, we were one big soul. Forty days before our conception, G‑d took our "big soul" in His hands and he split it into two pieces. The work of finding our soul mate is finding our missing half.
So how do we find our other half? We have to first begin by perfecting our half. In other words, we have to really know ourselves and be the best "half" we can possibly be. Your soul mate is out there, that's not the question. The question is: are you where you need to be to find him? Are you recognizable to him? Don't forget, he's looking for you too.
As for the "guarantee," you want one of the most powerful things about being in a relationship is that there are no guarantees. Faith and trust are such huge components in a marriage for this very reason. That's why our Sages compare the love between a man and wife to a fire. It is not static or calm, nor is it certain. It's not supposed to be. That is the beauty of a committed relationship…allowing someone into the most vulnerable and hidden places of our hearts trusting our emotions will be well received.
It is said that there are three partners in a marriage: the husband, the wife and G‑d. Until we meet our soulmate, it's just two partners… us and G‑d. This applies to that relationship as well. Because G‑d does not typically grant us a bird's eye view of His plans, we need to constantly bolster our relationship with faith and trust. We need to trust in our depths that He is guiding our steps towards our ultimate purpose, towards the "completion" of our soul.
Another strong component in marriage is communication. Communication is the essential ingredient to every healthy relationship. Since you are preparing to meet your life partner, it's important to practice communicating with your other partner, G‑d. Talk it out with Him. Some people call it prayer, but it could just as well be called communication.
Your "someone" is out there, looking for you. Be the best half-soul you can possibly be and G‑d willing, your steps will be guided towards each other sooner than you know it.
Blessings,
Rachel

As they set out from their place above, each soul is male and female as one. Only as they descend to this world do they part, each to its own side. And then it is the One Above who unites them again. This is His exclusive domain, for He alone knows which soul belongs to which and how they must reunite.
– Zohar (Book I, 85b)
Dear Zohar,
Meet a dissenting opinion as mentioned in Ben's comment below. Attached is a translation of the pertinent portion.
Rambam
Rambam teshuva #436
... As for [the Gemara on] marriages, it refers to unique circumstance where Hashem elects to intervene whether as a reward or as a punishment. For example, if this individual did/does an outstanding and phenomenal mitzvah that makes him/her worthy of an outstanding and phenomenal partner Hashem may intervene to match them up together. So, to someone who deserves constant battling [one example is a bully] Hashem may elect to match him up with someone who can take care of that.
However, this is pertinent only to those who make themselves worthy [for this special attention, whether for the good or bad].
The writings of Moshe ben Maimon zt”l