I used to be with a girl who had OCD, and we worked through it.
Is he aware of your OCD? If so, and if he is a saint, then talk to him and explain.
Would you feel more at ease if he washed his hands like you do? I did this for my ex, we washed our hands together, it became a cute little relationship things, picture postcard of 2 people washing their hands together, it was a very very small effort on my part but it meant so much to her and I'm sure he'd be willing to do this for you.
It's the key to all relationships, talk about it and find a solution that works for you both
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