Men do it because it sneaks up on them - which is EXACTLY how it is played by women, on purpose, to get the upper hand in the relationship.
If you put a frog in a pot of boiling water it immediately jumps outs.........men do the same.
If you put a frog in a pot of cold water and slowly heat it, the frog stays in the pot, constantly trying to adapt it's body temperature, until it is boiled alive. - Men do the same.
Many times, in a relationship, once a woman gets comfortable, secure.......she decides to try her hand to see how much control and relationship muscle she has. So it starts with a few subtle critiques........."Your hair looks greasy this morning"...."don't be so cheap"........."those pants look old"..................and they they wait to see the response. Or they withold sexx. Men, not realizing the "game" being played on them, try to make changes, to comply. To please. Because that is how we are built. You CAN and SHOULD un-learn this behavior.
I believe this is partially sub conscious in all women, meaning it is how they are wired. Remember, as the weaker sex, physically, the female developed to learn control of their "provider" through psychological means, as she had no other way. Then we get into the conscious area.......where this is done deliberately, on purpose, with the sole purpose of gaining hand in the relationship, of breaking your spirit. BPD's take this to an entirely different level.
My current Gf has not displayed any of this (18 months), but she is a rare exception.
Don't tolerate it. Ask yourself "is this something I would say to her?" Is this something I would say to a friend, or to someone I love" If not, it is out of line.
Sometimes, especially with a damaged woman, calling them out is the WORST thing you can do....they are actively LOOKING for an argument.....and now they have one. and you WILL end up the "bad guy"
Best response is a subtle withdrawal of attention and contact. Let her miss you, and she will appreciate you much more.