Hmm, in my experience, chemistry is like a spark that has the potential to grow into a fire. I can usually tell if that spark is there immediately, and then it grows after time.
It's very hard to define. In a sentence, I'd call it the measure of how effortlessly you can spend time with a person/talk to them.
I wrote a whole section on it in this one, if you're interested:
And to your point on instant chemistry kind of being like lust, I've definitely experienced how one can roll into another. I've definitely never had great sex with someone I didn't have great general chemistry with. But I've often had the opposite happen: I have great general chemistry with a person and really like them, but then it's just a total dud when we take things to the bedroom.
