This is so disturbing.
The right answer when a teenager says “I am so sure” about anything is to let them know that teenagers often feel really convinced they will always have the same strong feelings, thoughts and priorities they do at the time and that it is okay to try things out and experiment without making permanent commitments; remind them that under eighteens are not allowed to have tattoos for a reason - otherwise there’d be an awful lot of adults walking around, embarrassed of their tattoos of their teenage crush or obsessions.
An older man asking a teenaged girl if she’s ‘sure’ about something is so dodgy.