I had to drain an entire cuppa coffee trying to formulate an axiom here, and here’s what I came up with:
A hard limit is something you absolutely will not do even if it is a must-have for a partner or prospective partner.
Let me give you a few examples from my life. They’re from the D side of the slash, but they can give you a sense of the thing …
I knew a girl once for whom knife-play was a must-have. I didn’t care for knife-play, but it wasn’t a limit for me so I incorporated it into the dynamic.
I knew another girl for whom being urinated on was a must-have. I didn’t like it, but she needed it so I would occasionally indulge her.
And I knew a girl who had really negative verbal degradation as a must-have. “You fat stupid pig,” “you worthless dumb ugly bitch,” that sort of thing. That kind of degrading talk is a hard limit for me, so we were not a good fit and agreed not to go forward.
All of us, on both sides of the slash, do things we “don’t like” that are must-haves for our partners. It’s called compromise. But we never do something that is a hard limit for us. If we do, then it’s really not a hard limit, is it.
Hope this helps.