Changing dates...

So one of my best friends is getting married. I'm her maid of honor. She changed her original wedding date because of financial situations. Perfectly understandable. After that, she asked if my husband and I wanted to go with them on their honeymoon and split the expenses. This was because neither of us could afford it on our own and it will be the same week as my husband and mines first anniversary. We agreed and planned everything. Well I was going to book the trip next week when my husband got paid. She decided to change the date another week out, which is okay. I'm just not sure if I should book the place because, I'm scared she's going to change the dates again and I can't get the deposit back if she does. Is this wrong of me?