TMP began with him failing to attain Kolinahr because he was unable to stop V'Ger from stirring his emotions. He later got giggly and touchy-feely with Kirk in sickbay. He also wept for V'Ger in some cuts.
You don't remember him furiously slapping the phaser out of Valeris' hand in sickbay and then the aftermath of their mind meld on the bridge in TUC?
He came across as pretty upset there to me too. Other Vulcan's may not struggle for control all the time, but Spock is half human. From what I've seen, he was raised the Vulcan way in both verses and feels he has to live up to that. I always felt his whole story revolves around that conflict within. Which makes for good stories when he's thrown into traumatic events.