I am highly critical of my partner.

I have been with my partner for 5 years and I find a lot of his behaviour to be highly irritating to me and I make comments on a lot of it. I am aware I am doing this and it is not the person I want to be in this relationship. I would love to just be more open and loving and allow him to be fully who he is. I have worked through my manual for him and I can catch myself when I am acting out of this pattern but I am still at the point where I feel the urge to be critical or judgemental and then just give into it and not stop it.
I feel if I am to continue in this way then it is kinder to leave him as I do not want him to be subject to my behaviour and I don’t really want to live in this way and be the person I am being. I would love a way of finding some clarity through kindness towards him and experiencing our relationship in a whole new manner, because I also believe it could be a beautiful relationship if I allowed it to be.
Any insight would be greatly appreciated, thank you!