Hmmm one of your recent posts worries me. Going to pick it apart, if you don't mind
Maybe I am picking up on small things that I should just be letting go, or trying to talk too often (and that's why he's frustrated / annoyed with for me bringing it up)
Rule of thumb for me - if something small annoys me once, let it go. If it annoys me three times, mention it.
trying to talk too often .... for fucks sake. You're entitled to talk. There's a sense of proportion needed ofc, floods of words when someone's trying to work is the wrong time, but you're allowed to talk, @baffleddays . It's literally good to talk - the small chit chat is part of what holds most people together, the 'grooming talk' (grooming as in maintaining things). You don't come across as someone who chats away relentlessly and inappropriately.
Not responding to you is a way of training you to keep quiet, actually. My ex-H did it.
Maybe I am being too sensitive to anger (and so maybe his reactions are normal and I'm just being too sensitive)
when you're asking yourself that, something is deeply wrong. If it's a pattern that arises in several relationships, the problem is you. When the problem is only in one relationship - it's not. How are you with anger with your parents, friends, work colleagues, previous relationships? If this question has only just surfaced here - it's not you.
Maybe I am in the wrong to work late a lot and not give the relationship enough quality time... (and that's why it was okay for him to show disappointment / frustration when I was working late)
So when you talk, you talk too much but when you're not there you're also in the wrong? That must have been pleasant for you - getting home to a bad atmosphere.
Maybe he's just stressed and finding my niece or nephew difficult (and maybe that's why it's okay for him to have walked off during a day out)
This is an excuse. My kids' stepfather, when they were being annoying, stayed with us and actually quietly got involved, changing the conversation to something they like or suggesting they do something together like run over the grass and play tag, now and then telling them to cool it. Becuase he's taken the time to establish a rapport with them and show interest in them, when he says "enough", they listen ... well, usually :)
DP seems to regularly ask me to do small things round the house that are not unreasonable (e.g. he may ask me to pass him his coat) but he may ask me at a time when he's just as near to the coat cupboard as I am.
This to me is a giant red flag. He's getting you to do the running around for him. He's setting you up to be the one who is subordinate. He is responsible for himself but he's getting you to do stuff for him that he himself should be doing. Once is fine, three times is fine, but when it's a consistent pattern it's not.
He's getting you to run around after him, do his stuff for him, not disturb him, not get involved with your niece/nephew but throw wobblies about them, you can't talk too much to him, needy, and most of all, passive-aggressive and stonewalls you.
This is a man who's on a control freak run, and most of his actions are geared (possibly unconsciously) to setting the situation up where he is fundamentally in control of your life, and then to keep picking at you when he is.
Did he have a difficult childhood / difficult parents who didn't listen to him or respect his choices as a child? It's not always the case, but imo passive aggressiveness tends to take root when children are not listened to and become resentful.
From what you have said he's trying a bit to change but the indicators that you've written here are signs that this behaviour is extremely deeply rooted in him. Passive agressiveness works for the individual, on the whole. It doesn't work for anyone else, but it does for the individual.
Miracles can happen, people very occasionally do change and choose better ways of behaving, but from the outside it's unlikely to happen here. Not impossible mind you. But it will be extremely hard for you to keep alert for backsliding, and the pattern between you is deeply set now.