I think it is completely normal to feel what you are feeling. New relationships are powerfully exciting and flood your brain with dopamine that makes you crave your new partner at the expense of all other obligations in your life. It's a wildly fun feeling, but I don't think it means you're "falling out of love" with your existing partner. Since you say your boyfriend is the first you've had, perhaps you just lack the experience in discerning between NRE and love (which I don't mean as derogatory at all).
Now, it may be that an LDR isn't something you want for other reasons, but I wouldn't let NRE make you jump to any conclusions. Were you satisfied with the LDR arrangement before you met the new guy? The feelings will fade with the new guy in time. That powerful brain cocktail just doesn't last forever with anyone (which isn't a bad thing).
There's nothing quite as valuable as a long-term partner that is self-confident enough and open-minded enough to let you experiment and try on different hats for yourself without being threatened. The excitement fades over time, but something wonderfully valuable builds slowly in its place - a partner that knows you and loves you, a solid rock in life's storms. Maybe that's your boyfriend and maybe it isn't, but I would hate to see you throw away a good thing in the name of a new Shiny.