Ep13 was late into the night (or early morning here)

The confession did happen with hearts given per the school legend to Kaguya and she gave him a kiss.
And they used the cheap excuse none of them voiced their confession.
That's a way of closing the anime without straying to much from the manga I guess.

Kaguya going to Stanford was a given, nice touch he is the one to ask and had a letter of recomendation prepared for her.

Last scene was a proper end. I do not think they can milk another season after that. And a Standford arc would feel very different with the supporting crew out of the picture... even if a movie could work in a non academic setting.