I just need answers?

How come when we find someone we automatically feel like they the one for us we see them in our future we want to settle with them and just feel like they belong to us. But than things go down hill come to find out the person probably don’t see what you see or feel the same but made you feel like they felt the same made you feel like you found your soulmate? . Now your hurt but still see the future with that person you still feel like that’s your person you can’t unsee it but know you won’t ever have that person and don’t know why if they complete you. What do I do? Why do I feel this way and feel like this?
I just need answers?
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