Girls constantly tell me they feel no spark after the first date?

So I meet these girls online and the few times they do give me feedback they say they just didn't feel a spark. Like the girl I went out with tonight said we had good conversation and you didn't do anything wrong, but I just know what kind of personality meshes well with mine. Fair enough. What I don't get is why do they throw in the towel so quickly? Like I usually don't know what to think about a girl after only one date, but I do know if I want to see them again.

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My main frustration is I think they should put more time into a person then just one date. Unless the date was just horrible where it was obvious the conversation didn't even flow etc.
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Next time I'll just ask what she thought of me then depending on her answer I'll tell her yeah you weren't very exciting either. I'm tired this bs honestly.
Girls constantly tell me they feel no spark after the first date?
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