There really is not much you can do. It's a no win situation. You could ask her why she cancelled the trip. You never know, there could be a reason that you don't know. Or you could just say that you were sorry that she could not come on the trip.
In the last few weeks my XW has given me the opportunity to join her and our kids for meals out twice. The meals were fun and the kids and I had a great time. So, I asked my X if she would like to do something like a movie or walking her dogs. She replied "sorry, I will have to pass on hanging out"
Me/W: 46/36 D7.6/S6 T/M: 7.5/6.5 Bomb 12/05/07 D final: 03/03/09