Existence aside,finding out a person is your soulmate is a significant part of this "soulmate" thing. If you know the answer in the beginning, there would be much less fun of it. Actually, "not your soulmate" people are also playing a big role in your life. People just want things they wouldn't need to put further effort. We are all so obsessed with the goal and ignoring the fact that it is an essential journey before you make sure whether someone is your soulmate or not. Or maybe it's just a dumb, lame, evasive but perfect reason to get rid of your old, already dulled relationship.