If you make concessions out of fear or try to appease someone out of fear, someone is wiping their feet on your back.
But 'doormat' is a very subjective word. What it means to one person, might not mean the same thing to another. What it means to 100 people might not have the same meaning as it does for you.
My example, my point of view:
If you are afraid your spouse will leave you if stop sleeping with them and they are having an affair, I see that as being a doormat.
If your fear is greater than your sense of self worth. If your fear is the only choice you have.
Another example: If you don't divorce them and they are having an affair, but you're doing this because you know most affairs don't last, and you believe you can forgive them? You're bidding your time? You're not sleeping with them and you have some basic boundaries.
I do not see that as a doormat.
I see that as a choice you make. One that, while it is painful, you can be proud of.
Experience is a brutal teacher, but you learn. My God, do you learn. - C.S. Lewis
Life is usually all about how you handle Plan B. - Jack3Beans
Listen without defending; Speak without offending - FaithinAK