I've been through this with someone with OCPD (as said uphread, it is very distinct from OCD).
The view I had of my husband when I met him and we were dating was of a charming, kind, thoughtful, loving and hard working man. Once we bought a home together and married, that's when his true self slowly emerged over a few years. It was then that he revealed his appalling childhood. Looking back, massive red flags were waving but I didn't recognise them. His brother is a classic narcissist - I didn't know that word then and I just thought he was a pompous arse. His dad emotionally abused his mum and she suffered in bitter silence until she died. We very rarely saw his family anyway so I didn't see any red flags there.
I spent several years with him walking on eggshells. He inspected everything I did and then redid it in the "correct" way. Everything from the way I cleaned the sink to the way I poured milk. If anything was damaged or aged naturally - furniture, clothes, etc. - he would lose his temper, automatically blame me for the damage, then spend hours with a torch inspecting it (and I do mean hours).
He progressed to gaslighting me and stonewalling me. I didn't know those terms either back then and I didn't recognise that I was being emotionally abused. His strategy for me bringing up any grievance was to ignore me until I shut up, get up and leave the room, sigh, roll his eyes, flat out deny anything I said to him, or get annoyed with me. As an example - I once saw that a pair of my shoes, which previously I had lined up together neatly, had been kicked right across the room. I asked him, why have you kicked my shoes? He denied it flat out, even though it was blatantly obvious they had been kicked: they were scattered across the floor and on their sides. One shoe was scuffed. He just kept saying he had no idea what I was on about, but with this incredulous look on his face like I was crazy.
I went from a popular outgoing positive person to a nervous tense shell. I ended up with a diagnosis of anxiety and depression, and when I told him that I had been diagnosed depressed and that I was planning on leaving him, he changed overnight. Literally. He accepted everything I accused him of without denying it, he apologised for everything he'd done. He cut contact with his family and he went for extensive psychotherapy for months. He went back to the person I dated. That was three years ago.
Things are good now, but looking back it was exhausting, awful and he nearly broke me. I should have left him and cut my losses. But I only recognised the emotional abuse and the OCPD for what it was after many many years into the relationship. I did extensive research into helping him and onto personality disorders. I like being with him now, he is extremely thoughtful and lovely, and he has worked hard to change himself and is always keen to make me happy. But still sometimes I am resentful at what he put me through and still sometimes I think I should have left him. And every now and then I think that I hate him for what he did. It shouldn't be that hard.
My husband is very very unusual in that I scared him enough with my depression diagnosis and telling him I was leaving that he accepted his problems and sought help. People with OCPD and abusers very very rarely have that level of insight. I would advise anyone recognising these patterns to run for the hills. And then run a bit further.