I can do odd O/C things now and then. But I had a girlfriend with a mild form of OCD:
She sometimes carried hand sanitizer and washed hands as soon as she got in.
Didn't like to touch metal (unless handcuffs ) especially anything rusty.
Didn't like to touch cold, wet foods or any food in the sink.
Arranged movies categorically and alphabetically (of course she had a lot).
Arranged clothes categorically and chromatically.
Liked bottle labels all pointing forward.
Didn't like her routine being messed with and often needed to "emotionally prepare" for certain things.
Drove me nuts sometimes!