Fair enough, though there is a flirtatious look Spock gives Uhura while playing his Vulcan harp. I'm guessing (don't have any evidence) that this was the reason given for the relationship.Yes: in TOS there was no indication this could have ever been a thing. It’s obvious they did it to give Zoe Saldana something more to do, but it really came out of the blue and, for me, didn’t work with where Spock was supposed to be in his life.
But, I hadn't thought of the T'Pring aspect. Interesting point. I had taken the relationship with Uhura to be the logical idea of understanding humanity and it became more. But, again, my assumptions.
It's a fair complaint if it came out of the blue for you.