Is this normal to think about?

I know exactly how you feel. But I'm 18 so its more logical for me to be thinking about spending the rest of my life with someone. I have an amazing boyfriend, but sometimes I think about the future and I wonder if he really is the one or if "the one" is someone else? But then I realize how amazing he is to me and how much I love him and I stop thinking about it. I guess just go with it. You never know maybe he is the one and maybe there is someone out there who is more perfect for you.