@Anonymous - So the cat one i just came up with right then and there. I find that inserting humor, saying something kinda silly, helps me remember this is all silly OCD. The statements can change, just so long as the content is that you acknowledge but don't interact with the fear. So to a thought of " I don't want to marry him" I might say " "oh well, he wants to marry me, can't wait to eat some wedding cake!" or " maybe I don't want to marry him, maybe I do, ill never know unless I give it a try, I choose to marry him" for me, when I was experiencing the ROCD my therapist at the time told me, when your brain in a confused stormy state, its always best to stay on course, don't jump ship, don't make any changes. So at that time, I was dating the man, so that meant to continue to date him, no breaking up, no stepping back, no jumping ship, but doubling down on the course I was on despite everything inside me SCREAMING "I am making a mistake, he isnt the one, Im not even attracted to him, this will end badly" i stuck with him, and as the storm passed, all those statements slowly reversed themselves and now we are coming up on our 2 year anniversary and I'm SO SO HAPPY i didn't let OCD take the love of my life away from me.
So for now, double down. Give yourself a goal, tell yourself "I'm going to commit to this relationship and marry him. if i don't shake these doubts in 6 months, then ill re-evaluate , but for now, its on like donkey kong" and typically what happens is when your "re-evaluate" period arrives, your already 5 months past the initial doubts and laughing at yourself for ever doubting in the first place.