What do I do when a friend "unfriends" me?

Just be honest and tell her that you have done nothing but enjoy and work at this friendship but to only receive something negative back, let her know that you would miss her but if that's what she wants theres nothing left for you to say as you thought your friendship was a lot stronger than what has been brought to your attention. This will give her room for thought and time to realize she has lost a good friend who has made effortless attempts to bring you both closer but has only reciprocated selfish emotions back. Remain open minded in case she gets a reality check and admitts her behaviour was un called for, and this will help you both rekindle something that was unnecessarily broken, and she will realize. You sound very clued up and on track to what has been going on, but good friends do have their moments so it is always worth leaving the door open for them and not slamming it shut. Hope you get what you deserve and that your friend realizes her wrong doings, take care and congrats on your wedding,x