Is it so wrong to date my best friend?

That scrapbook sounds like an excellent birthday present to me. Make sure to take pictures too. Idk, this one is a catchy question for me. Why? I've had male best friends since the eighth grade. No romantic interest. Just friends. I still am friends with some of them in fact, at a distance, but still good friends. However, in your particular case, if he jokes around that "you'll be best friends forever and get married and have kids and live in a lake house", then I believe he feels the same way about you too and does have some romantic interest in you. However, it is not good that you both "assume what you feel for each other". You know what happens when you assume. High school is only once and a very precious time. You'll know just how precious when you're over the hill. LOL. Getting back to the subject at hand, if you don't dare to ask him about his feelings for you, then ask him if "he really plans to get married and have kids with you or if he was joking around". I'm serious. You must find out no matter what. Even if you don't dare ask in person and choose to do so by text message, fb, or whatever, the thing is: it is important you find out so that you don't end up waiting for someone in vain. Youth is too precious to waste it in any way or manner and when one is young like you, one thinks you can "wait forever". Unfortunately, time goes by quick so it is important that you know his true feelings towards you. Ultimately, do whatever you want, but that's my piece of advice for you regarding your best friend.