Destination wedding madness

So along with planning our own wedding, my fiance and I have been invited to a destination wedding with a months notice, and he is a groomsmen. It was expensive (about $700) in airfare, and his cousin (the one getting married) said that he was going to pay for our hotel and not to worry about it.



So first, we find out that the venue and place we are staying is 3 and a half hours from the airport. So we have a 6 hour flight and then all that driving. Annoying but whatever we can deal with it. Then, I'm told that his cousins FMIL is apparently the one paying for the lodging and has said that my FH can stay there, but I'm not allowed to sleep there because we arent married and sleeping together is a sin. There are two other couples so now this leaves 3 of us girls to have to figure out a place to stay, mind you this venue is in the middle of no where.
Is this normal? How are you going to last minute invite people to your destination wedding and then dictate who is allowed to sleep where? Also, who is anyone to throw their religion on other people? I understand that shes paying for the lodging, but maybe she should focus on the fact that shes in her 3rd marriage. Not on other ENGAGED couples sleeping in the same bed. Also way to tell us after we book nonrefundable plane tickets lol. I just think its crazy to expect us to travel almost 10 hours in one day and spend all this money, say you're paying for the lodging and then basically take it back after we already booked everything.
If you are having a destination wedding would you ever dictate where you guests could sleep and what they're allowed to do?