What if she says I don't see you that way. But she'd like to be my friend? She hasn't said this but just in case.
Move on.
Your mindset should be that she's the one losing out.
She might realise her mistake at a later day - or she might not - don't live your life based on one woman's decision.
You're young - plenty more time - plenty more women,
If I get this statement in a social situation, she'll get no more than an uninterested-sounding "No worries" or similar... then I'll just go talk to someone else, or do something else.
If it's by text, I simply won't answer - unless she really pushes for one... then she'll just get something similarly dismissive (but without being a d!ck about it)
No need to be rude, just become 'distant'.
A few yrs ago... I'd recently become single after splitting from a marriage, and had a date with a chick I'd known for years while married.
It went nowhere, there was just no mutual spark.
Then a few weeks later I got together with a mutual friend - The 2nd one (the woman I was seeing at the time), asked the first one why the date went nowhere, and was told
"I just didn't see him that way"
Weirdly though.... It's amazing just how interested she became when she realised how happy the 2nd one was with me.