Is being "too nice" a good reason to reject anyone?

I met a friend today and told me about this one instance where he asked a girl out for coffee and she said you are "too nice" to go out with sorry.
So it is a genuine reason or she was just rejecting him politely. (I think the second)
But if you think the first then what is the good amount of nice to get in a relationship according to you?
Updates
11 mo
Sorry guys for the incomplete question. The girl he asked to coffee was his college friend and he asked her out on a date kind of thing.
Is being "too nice" a good reason to reject anyone?
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