Is there really a way to **know **the right person or is it something developed over time?
I’m only 20 years old, but from the wisdom taken on faith from what the wise tell me, and little of my own reasoning, only a wise man at the end of his life (or a wise woman at the end of hers) will be able to discern relatively correctly who would be the best spouse for him/her.
I don’t want you to dispair, but most of the “choosing” is already done for you. Your location, social class, financial situation, race, and sex all have limited who you will probably end up. Coupled with the immaturity of youth (ignorance, sentimentality, etc.), you are probably not going to pick the best person. You might pick a comparable person, but not the best. There is a reason that traditional society have elders arrange marriages: it avoids many of the problems I just mentioned. Studies show arranged marriages are happier (unless they were politically motivated).
When someone says that they just “know,” more often than not, it is a politically correct way of saying “I’m acting on impulse” or “I’m reacting under cultural pressure.” It is the sentimentality of the age. As another has said, it ends up not in divorce only by accident, by pure luck.
I know for us men at least, we are always “hunting” for the ideal woman. We stick to the best we’ve found, but once we find one better, like say the young college age girl next door, we can be seriously tempted to go after the “better” girl. I think this is also why, in history, it is virtually always men who have multiple wives in history, rather than women having multiple husbands.
So, if you want to take the advise of an immature 20 year old

I would say that, mirroring what I experienced above, it’s
okay for a relationship, at least at its start, to be grounded mostly in romantic feelings and inflatuation. You just want to make sure that there is something each of you have that will stabilize the relationship too: something that doesn’t fluctuate like emotions or sex

(My parents’ relationship is based mostly on sex, and once they got older and had three children, everyone in my family has suffered from it. Avoid fornication: its lures blind you from reality, and keep you in a bad relationship).
You also have to make sure you don’t lose yourself to the other person: don’t abandon yourself and become what she wants you to be (I use “she” because I am a young man), rather take what you are and use that for the sake of her wellbeing. It might turn out, if you “be yourself,” rather than “someone else,” that you two are not compatible. If you are “someone else” though, she might love the mask, and if you as yourself are not compatible with her, this sort of relationship is not only bad for you, but even worse, it will ultimately break the other person’s heart, and waste her time.
Here:
ewtn.com/library/MARRIAGE/3GETMARR.TXT
One more piece of advise: your “soulmate” is your spouse. Once you get married, there is no “I am actually suppose to be with her!” She is the one you are one flesh with, and she is the one you are destined to be with (a generalization, of course. There are complications).
(“Soulmate” is that is actually a Platonic term, not a Christian one. The pagans thought that we were originally one body with our “soulmate,” but the gods split us apart for our sins against them. So, intercourse is a kind of punishment, an attempt to fix what is broken.
The Christian view, however, sees love as a life giving choice, and that this choice between the two make them “soulmates” (you choose your soulmate: he/she is not preassigned), which the “ritual” to make two one ends in the marriage bed, with the two becoming one flesh. Marriage is a growth in a living thing, not the hasty repair of a dead thing. This is what Benedict’s
Deus est Caritas is about).
Christi pax,
Lucretius