19 yr old son and his girlfriend have been together almost a year. We have been planning a holiday to somewhere since before they got together for later this year. Once they’d been together a while we invited her on the basis that they both pay 500£ towards the cost of the holiday (am yet to receive anything from either of them), It would still be costing us about an extra 1500£ for her to come. Last week she split up with the him, however today they have decided to get back together. Balance is due Wednesday. Husband is adamant he no longer wants her to come, son and girlfriend think all is ok and I’m really torn. What do I do?!