Wedding Etiquette #5

[OOHLALA]

I have a new question to ask:
If you are familiar with my first few etiquette questions, you will be aware that my good friend and I are both getting married soon.

Well, at first she was getting married in May, which was short notice, but I was prepared to make it happen to attend. My date was and has been set:9/8/01.

Ok my dilema)sp?) is: We were supposed to be in each others wedding, but then after a while
and realizing how fast that (May) was coming she pushed it back to August 21, 2001 to hold it on his family cruise they already had planned. And becasue my company only offers 2 weeks paid vacation, I had to decline her offer to be in her wedding. This is because she is going on a 5 day cruise which at that time I will not have any extra time to take for leave and I will be leaving from my job on the 28 of August.
How would you guys feel if I backed out on you and we are really good friends. Would you be understanding and realize that I did have ny date set first and that it would be an imposition on me to attend. Or would you back out of my wedding since I could not attend yours, even if you could attend?