Have an opinion?
Yes. Absolutely. Especially if it's on your credit card. And then I would go and bring a friend.
And yes, in the reverse situation, you should offer to pay for at least your share of the trip.
Completely fair. I paid for my side of the trip but he's offering to cover my loss as well as his own. Don't know whether to let him or tell him I don't need his money!
That's very nice of him. I would personally just take his half (and still go on the trip).
You cannot undo this action. The opinion owner is going to be notified and earn 7 XPER points.