Spock spent Discovery season 2 learning to deal with feelings and his humanity. He learned to trust and love Michael again, to reach out to her and depend on her.
And then she is ripped away and he can literally never speak of her outside of his family again.
That kind of trauma might get a person to: Become closed off, not deal with their feelings, re-retreat into their Vulcan side because everything about being human hurts like hell and the one person that loved you and understood is gone forever.
It might make that person reluctant to trust people. Until you meet the right person that is kind, generous, understanding and cares openly and deeply…
The bridge between DSC Spock and TOS makes sense to me if I see Spock as someone dealing with a trauma, which he is shielding himself from. It adds another layer to his fear of his human side – there is a loss there that is profound which he don’t know how to deal with and has promised not to talk about.
At this time he is barely on speaking terms with his family – the only people that knows about what he’s going through.