I didn't have a "spark" with my boyfriend on our first date, I had this strong sense of familiarity, like I already knew him, and a total ease in being in his company. There was nothing triggering or anxiety-inducing about our correspondence, our dates, our texting, it just flowed naturally and I just suddenly couldn't imagine being without him. No games, he always texted and called and never left me wondering.
I think dating is so brutal and so geared towards instant gratification, that you can get a bit blunt in your approach sometimes, as that seems to be how everyone else operates online after a certain amount of face swiping. For me, a lot of the time when I felt a "spark", it actually was this deeply triggering thing where my nervous system was activated by someone being a bit hot-and-cold, emotionally unavailable, or player-y, or it was a booze-induced spark based on them being really physically attractive to me but there was no real compatibility beyond that. One key thing that pointed this out to me is I could go on a first date with a really "hot" / "high status" guy, get love-bombed, he'd promise the world, and immediately get anxiety the next day, and the day after, and the day after, when i didn't hear from him. Ball was always in his court, and that was without me knowing this guy AT ALL, and with the guy exhibiting more red flags than a soviet parade. It was never about a "spark", it was about me getting this big ego boost and abandoning all of my senses as I tried to maintain it.
I agree entirely with @ivebeenthatgirltoo above. A lot of this stuff tracks back to our own childhoods, and sense of self worth, and ideas of what romantic "love" looks like, when the reality is actually a lot more muted, peaceful and "boring" (but amazing!)