I'm the slow burn person. And I enjoyed the NRE thing. But I am leery of saying "love" too soon.
Because I LOVE the NRE feel. That doesn't mean I LOVE the actual real person yet, in depth. I'm viewing them through rose colored pink fluffy lala clouds of NRE. (You can look up the neuroscience of falling in love to get all the hormone names and what they do. ) I am drunk on that high, so I'm not in my right mind and I know it.
So in the transition time, I gush all I want by showing them affection/caring in different ways. If they tell ME they are in love I smile and tell them "I know. Thanks. I'm just a slow burner so don't get upset if I'm not ready to say that word out loud yet. But I've really fallen HARD in LIKE with you!"
And then I just sub out the word "Like" -- when the impulse is to use the word "love" later on. Sometimes quietly. Sometimes really gushy.
They usually don't mind me gushy going "I really, really LIKE you! Wheee!"