I have a SO like this. 8 Years now, it gets more easy over time, a bit at least. Real OCD is no joke, its like being insane while knowing. One knows on a logical level that it makes no sense to do this repetive actions, but has to do it anyway. Its often not only external stuff like washing hands, rotating objects till “they feel right”…a lot of ODC action are internal. Like saying certein sentences internal for X number of times.
As a Partner that can be frustrating causd you want to help the person u love but there is nothing u can do. You just have to accept it is like it is.
The internal permanent tention can be very exhaustig. Most people can have ‘empty head’ moments where you just chill and think nothing to relex for a moment. When u have strong OCD that dosent exists, every second your head is rotating, doing loops of things in your mind. Even simple things like catching a bus at a certein time can become extreme hard tasks cause you ‘cant just go’ no. U have to do all the internal and external OCD tasks before u can walk out the door.
All u can do as a partner is having patience, lots of it, and understandinf that the pressure to do this OCD tasks is as real to there brains as the need to breathe to us.