Is it a bad idea for an 18 year old girl to travel alone internationally? [closed]

I've been planning a trip to visit my boyfriend of 5 years (yes I've met him but he came here) in Europe. I'm 18 years old and my parents are fighting me on it relentlessly. I have the money and everything, but they are scared I'll be involved in a terrorist attack/get kidnapped for human trafficking. I've tried to convince her that it's not as common as she thinks, people travel solo every single day and are fine. How can I convince her I will be fine? Or am I wrong? Anyone with travelling experience is especially welcome to give their input.