Take it for someone who is getting married (in 100 days to be exact)
Choosing someone to be in your wedding can be VERY stressful!!! Especially when you have a LARGE family like I have!!!!! There have been a case when I wanted one of my soon to be sister-in law to be in the wedding, and she just found out she is pregnant and can't be apart of the the ceremony. So I had to find a replacement, I asked on of my closest cousin to be in the wedding. She totally UNDERSTOOD, and stepped in. Now from what I gathered from planning this wedding, it can be EXTREEMLY stressful on the bride, and although my cousin wanting to be in the wedding in the FIRST place, she undertood that I have a HUGE family and that I had to include my sisters, and my hubby sisters, and my best friend!!!! (Which equals a total of NINE brides Maids!!!!) I really wanted to include my ships (line sisters) but I couldn't so instead they are all hostesses!
I say be in the wedding, and if you are having second thoughts about it, PLEASE tell her ASAP so that she can find another replacement!!! Just think if you were in her shoes! I am pretty sure she is stressed out enough at the fact that one of her bridesmaids can't do it anyway!!
I hope this helps!!