It may happen, though, that you have your heart set on the arrangements as they are for whatever reason, and are prepared to dig in your heels and tell your errant maid to like it or lump it. Unfortunately, the only time one can ask a bridesmaid to step down without fear of repercussions is if the friendship is irreparably severed between the time you assign her the job and your wedding date. If you want to keep the friend, you have to keep the bridesmaid. Or at least the appearance of wanting to keep the bridesmaid. Because you complain incessantly and you're making my engagement a waking nightmare.
Few friendships can survive such frankness.
However, there is a sneaky means of defusing the situation with a rather high success rate. Make it sound as if you're doing her a favor by being considerate of her stress level, rather than your own. Lisa, you've been so unhappy since I asked you to be in my wedding. I really didn't mean to cause you to be so upset by putting you in a dress you don't like and pairing you with a guy you'd cross a busy street to avoid. I hate seeing you troubled over all these wedding arrangements.