Complicated relationship

Olivia • I'm Olivia! I'm 19 from Mississippi. Any questions, figure out how to ask 😐🙃
So. I'm 18. And my boyfriend is 25. Wait before you say that's crazy!! I act more mature that the average 18 year old and he's the only person I've met to take a relationship seriously rather than high school or college boys I've met. But my parents don't see it that way. And because I still live in their house until I graduate, they won't even have the idea of me dating him. They've grounded me and told me to never see him again... They won't even meet him to see what he's about. My dad is convinced that he knows exactly "what a 25 year old wants from an 18 year old". I guess I just want some other people's opinion on this.