I remember my first love and it was just a crazy tangle of emotions - excitment, joy, insecurity, pleasure - all at once.

Everything was absolutely new which made the entire experience both wonderful and scary.
I think the biggest difference between my first love and a long term love is the focus shifts from all about what you are feeling (albeit with a needy attention given to how they feel primarily in regards to what their feelings might lead you to feel/experience) to a true concern with the person you love in addition to yourself. You learn how to become partners with another person, not dependent upon them. Just my opinion though.