I'm not sure if I'm misunderstanding or if Amy is misunderstanding the ticket issue.  It sounded to me like the host couple received their 2 tickets for free, but invited the other couple to go along who had to purchase their own 2 tickets at face value.  It sounded like the invitees were complaining at paying the whole price of the tickets rather than the host couple paying for half of the additional (non-free) tickets.   In that case, I don't think it is the business of the invited couple to know how much the host paid for their own tickets.  If they went out to dinner with another person and that person received a senior citizen discount on their food (for example) would they demand that the person pick up part of their tab to balance out?  Each person obtains a ticket and pays whatever the cost was for their own ticket which is what happened here.  The hosts *could* have offered to split the fee but were not obligated.