When you live with someone, there will be little habits the other person has that wind you up. There may also be more serious issues that require discussion and some sort of action.
For example, my last LTR, he snored. He snored so loudly you could hear it if he was upstairs with the bedroom door shut and I was in the lounge with the TV on. This was a serious issue because obviously it affected my sleep and therefore my performance at work. When he did eventually get it checked out, it turned out he had sleep apnoea and needed a CPAP.
Little niggles: He used to feed the cat and leave the empty pouch on the side, above the bin. He used to smoke in the car when I was due to use it the following day and he thought cracking the window would mean I wouldn't notice. He had a habit of repeating a phrase when he was talking - like "Yeah babe but the thing is, the thing is, the thing is, Jose Mourinho has never, has never, has never blah blah football talk"
He had little niggles with me. My habit of always going for the punchline and laughing at situations that he thought should be serious. The fact that I tend to deconstruct films and TV rather than just "enjoying the experience".
With all of these, he would maybe mention it once, or say "Oh god, you and your bloody analyzing brain!"
He also had some serious issues with me which required work on both our parts to find a compromise (step-parenting/household related - too long and boring to go into, but we worked it out.)
If someone is criticizing the way you BREATHE, then I think that person should not be in a relationship that involves spending more than about 8 hours together at a time.
Are you his first serious relationship?