That's only really true for the games.
To me, I just don't see it that way, I saw their relationship as family rather than romantic, I do agree, Cortana is one of Chief's closest friends though but intimate can also be in a non-romantic way.
We can agree though it's definitely not a I wanna kiss you/I wanna run away with you relationship at least
It also feels a bit weird cause of the whole aspect of Chief seeing Halsey as his mother and Cortana being based off Halsey's brain, Lol. Just to me makes the whole romance theory come across as a bit weird.
Well, at the end of the day, the larger Halo fanbase is gonna take their que from the games. And frankly, even as someone who likes the larger Halo lore, and universe, ever since 343 took over, there's way too much shit happening outside the games, and it often doesn't corelate particularly well with their storytelling in the games.
As for Cortana being based off Halsey...sure, but you only need to look at the difference between Cortana and The Weapon to see how they can still be incredibly different on an individual basis.