Most welcomed new things in our lives are fun and exciting. What more heart racing then: the first phone calls letting you know you were on their mind; the holding hands that show the unspoken commitment; or how about wondering if they are dreaming of the same future together while getting lost in each others eyes.
As long as you can say that you don't love the person any less, then it is not the love that went downward, it was the falling in love that yielded. Everything that was new and exciting you experienced. By experience comes knowledge. You know you are top on their mind, you have made even larger/louder signs of commitment, and maybe you ARE sharing the life you dreamt about together.
Hopefully it was the person you fell in love with, instead of the excitement of falling in love.