Recently I have been having some issues with one of my bridesmaids. During our dress shopping for the bridesmaid dresses, I had to pull asides one of my maids-of-honor to make sure that she could handle the pressure of being a maid-of-honor (she is having a lot of stress in her normal life that was causing a lot of tension). She finally broke down and told me that she wasn't going to be able to handle it and asked me to replace her as the maid of honor, but still wanted to be in the bridal party.
Fast forward a few weeks and I get a text from her stating that she wants the position back, that she felt as though I had forced her out of the position and things are going well enough in her life that she can take the position back. I have already asked one of my other girls to fill in for her and I feel more comfortable with the new girl being reliable for the "job". 
I just need advise on what to do. I love my best friend, but I feel like I cannot depend on her for the role.