i had the same thing happen to me, honestly, your friend is not happy for you, she jealous and doesn't know how to get over it. you have to be honest with yourself and just say hey,we're friends, but she is not happy for this portion of my life, she makes excuses because she is not genuinely happy for you. it's brutal truth. but it's truth none the less. i had same happen with my best friend(or so i thought she was) . it's not a hard deision at all, you now have to be honest with her as you would've hoped she would have been with you. Just explain to her that you understand she has things going in her life right now and that you need a MOH that is able to be a little more hands on and involved then she's able to dedicate herself to being right now and that you will need to ask somoenone else who has the time to dedicate for your special day. while it's personal, it's about handling business. besides you want a personn who's gonna be your MOH because they truly will stand up for you in that respect, not someone there because you asked but half heartedly does the job. don't compromise your happiness, for someone who isn't really happy for you.