Technically, the roots of the relationship are in TOS with Leila Kalomi, where Spock abandoned a relationship in his youth for his career. Chapel was just an extension of that decision and NuUhura is just this universe's Leila rather than this universe's Chapel. What's clear is that he was headed to do the same to NuUhura (already being nervous about the implications of their relationship in the movie). Whether the destruction of Vulcan and Amanda will change that arc is something the sequel will have to explore. I'm more worried that NuKirk's risk taking habit has had no time to mature before being given command of a starship, coupled with his frightening belief in his own opinions to the point of not only ignoring advice but also the orders of superior officers. Interestingly, the writers have indicated that the speed of his promotion is something that they intend to explore based partly on fan commentary.