As I've probably noted on some earlier thread: Of course
Kirk fell in love with her instantly; Flint created her, and his genius was such that it's a wonder all three Enterprise officers didn't fall all over her, including Mr. Spock (heck, if he could swoon over that empty-headed Droxine...)
The extent of Flint's genius makes every element of the story possible, from the gigantic (partly pheromonal?) allure of Rayna to the Brahms waltz that Spock plays. He controls everything
while Kirk et al. are on his planet, including the resolution of the ryetalin business; he could have whipped some up, uncontaminated, anytime. The Enterprise officers were puppets; like the crew and ship, they could have been suspended/miniaturized anytime (halting the epidemic's progress as well).
Flint could have anything he wanted - except that he couldn't succeed, despite repeated attempts, to create a Rayna who will love him like he wants her to. That's his tragedy and the point of the episode: Living thousands of years, and accumulating all that knowledge and having all that time to develop skills, has the tradeoff that you will always outlive anyone you fall in love with, see that person sicken and die, go through that dozens of times, and then
you can't succeed in creating a replacement to avoid further heartbreak.
Kirk was just a conveniently visiting ordinary human who Flint thought could help kick-start the latest Rayna. At least we do get the epilog, to show (i) that Kirk was chewed up & spit out by the whole experience, (ii) Bones' compassion for Flint, and also for Spock because of what he'll never experience, and finally (iii) Spock's compassion for Kirk: "Forget."