Maid of Honor Advice
Once asked, is it okay to say no to being Maid of Honor?
This is a very sensitive issue, and as such the answer is inevitably yes and no. On the one hand, it's considerate and fairer to the bride to decline being maid of honor from the start if you know you won't have the time to meet all the maid of honor's responsibilities, or if you can't afford to buy the bridesmaid dress. It's better for the bride if you're upfront and honest. On the flipside, however, it's not really that simple.
A bride usually puts a lot of thought into who will be her maid of honor, and makes her selection based on who she believes she can trust and be supported by. Asking a friend or sister to be your maid of honor is therefore an emotional act which involves the bride putting herself out there and saying, "You're the one I trust with something this important." The bride may see your declining her offer as an emotional or social rejection.
So basically, the short answer is that saying no might realistically create a rift in your friendship which you will need to work hard to fix. The best answer I can give is to serve as maid of honor if at all possible.
If, for whatever reason, you do need or want to decline a friend's offer to be her maid of honor, the important thing is to carefully explain your reasons and emphasize how much you do care about the bride, her wedding and her happiness. Explain how honored you are to have been asked, but why you don't think it would be fair to the bride for you to accept such an honor. Emphasize the importance of the maid of honor's responsibilities and how, despite your best intentions, you do not feel you could fulfill them as well as the bride deserves.
Then, move away from the maid of honor offer and demonstrate your sincere interest in the bride's wedding plans, excitement and new groom-to-be. As long as the bride comes to understand you are still her friend and still want to be involved in her life, the possible rift in your friendship will hopefully be short lived.