Eh.
That's your opinion and may be true for you, and may be true for you just because you want to believe it.
That doesn't mean it's true for everyone.

Might as well say there is no such thing as one god.

I mean:

Many say they would like to find and have a relationship with god.
...Some people are motivated by their religious faith, and want a more personal relationship with their god, strive to be better at their beliefs, actually hear voices, whatever.
...Some people don't believe in god, but they see community when they go to church, see people and how they behave when they feel they have a relationship with god, real or delusional, so feel their life would be improved if they could "drink the koolaid" so to speak and have their own "relationship with god" and the quality of emotional life they observe other people having because of it.

By saying something like "there is no such thing as just one soul mate" is little different than saying "there is no such ting as one god.

You might be completely missing the point of what and/or why someone is telling you "they would like to find and have a relationship, with a soul mate."