I can identify with the OP. One of my ex-girlfriend's best friends had the same thing. Holding the door for someone is courteous. Though certainly not something major, it is a form of self-sacrifice, doing something for someone else. Part of the equality movement for women included being self-sufficient, which is seen to be a characteristically male trait, but it has detracted from a sense of community (which we've lost for the most part).
As far as I'm concerned, kill 'em with kindness. Keep doing it, keep pissing them off, keeping repeating "I'm not doing because I think you can't, but because I can and want to." If that line of logic doesn't get through, you're a smarter and better person because of it. Though I try to be chivalric, I can just tell people that I got used to grabbing the door after hosting for a restaurant for a year and a half.