Stress and OCD feed off of each other into a rather unfortunate positive feedback-loop.
The best partners for people with OCD are the ones who know how to talk us down off the ledge.
Supporting someone isn’t the same thing as fixing them. Respect that what they’re going through is real — even if you think it defies logic. If touching a shopping cart in the grocery store made my OCD flare, I’d carry all my groceries with my two hands instead of using the cart.
I wouldn’t go to school for months on end because school made me Earth shatteringly anxious.
But it is nowhere near as hard as being the one with BPD.