Need some input

So I’m 17 and I’m in my last year of high school. I’ve been dating a guy since the end of ninth grade. I love him and he’s my best friend but everyone seems to have no faith in high school relationships ever going passed graduation. Whenever I think of my future I see him but everyone says you need to experiment after high school but what if that’s not what I want? I’m not going to break up with him because of what people think of high school relationships but I’m just wondering on everyone’s opinion?