Don't get me wrong: it's awesome being in a long-term relationship where you're utterly comfortable and emotionally intimate, blah, blah, blah. But pretty much everyone I've talked to agrees that the first three months are always the most exciting; everything is new, and anything seems possible.
In fact, the first three months can be deceptive. I tend to idealize everything and become completely convinced that someone is the love of my life, only to realize after three months that they are utterly wrong for me. But that's another reason that the first three months are the best: it's always fun, no matter how it all turns out. If at the end of three months it's all over, no big whoop; it was just three (fun) months of your life, and now you have a better understanding of what you don't want in a relationship. Thus, this celebration of why the first three months are the absolute best.