This is a tragic story, we don't know enough about the girl to understand. As a 12 year old, her side of the story needs to be kept confidential.
It is shocking that a not-very-bright student who met up with someone on Tinder, believing her to be a consenting adult could have his life wrecked because he believed her lies. It appears that he was straight with her. I have also seen 12/13 year olds who look much older than they are.
It is also shocking that a 12 year has lost her childhood and felt that it was appropriate to be on Tinder.
Just a sad story all round, shows the importance of boys not just getting informed consent, but making sure the girls can give consent, which can be a challenge when you can get false ID for less than £20.