Family member 1 (host) has a huge garden and hosts gatherings often over summer.
A BBQ has been pending for a while, involving host's family, extended family and friends and neighbours. The purpose of the BBQ is to celebrate two family member's birthdays that are close together.
When first discussed about two months ago, it proved hard to find a date where both birthday family members were available. Also host had a dilemma as to whether to have it on a Saturday or Sunday-given a lot of people have busy Saturdays over Summer, but people work on Mondays and may not want long drives/booze etc.
One of the birthday family members is in a LDR and only sees their DP some weekends, DP always leaves on a Sunday morning as they work on the Monday-it is difficult for them to get Mondays off at this time of year. Host is very aware of this, but it wasn't discussed specifically while making arrangements.
Last time the DP visited everyone was trying to figure out what weekend would be best and decided on this weekend. This was around a month ago.
In the meantime birthday family member's friend asked if they could spend some time with them the Saturday of this weekend-birthday family member mentioned the BBQ and said they were welcome to come to it (which they knew they would be) and mentioned to host who said yes that's fine but then later on, they said to birthday family member 'You do know It's on the Sunday, not the Saturday?'
Birthday family member hadn't known this and is now upset as their DP cannot be at their birthday gathering with them. Their DP is upset because they were looking forward to coming.
Host has said birthday family member should not have assumed it'd be on the Saturday. They've also given their (valid) reasons why the Sunday would be better, and said they discussed it at length with other family members. It had not been specifically mentioned at any point to birthday family member however, despite these discussions, which has riled them somewhat.
Birthday member accepts that they assumed and shouldn't have but feels that host should have specifically mentioned about it being on a Sunday, and should also have perhaps been mindful that birthday member's DP cannot 'do' Sundays when making the decision.
Other info-host reckons they mentioned the date (not day) to both the DP and birthday member. Neither remember this conversation and also have said that this would have been weeks ago and they mightn't' have been mindful to look up whether this was a Sat or a Sun.
Host is upset as birthday member is disappointed and upset and has said they won't attend for the whole day-they were expecting a nice day with their DP and they often have to attend events alone due to LDR and this was going to be a nice day for them, now It's just 'meh'. They're not especially close to anyone else there other than host, and there's a huge age gap with all guests and them too.
Their DP was meant to be doing some of the cooking to give host a break to speak to their friends-which is a small issue.
So was birthday member wrong to assume and should have asked? Was host wrong to assume birthday member knew the day? Should they have specified and/or thought 'hang on, the DP isn't free on Sundays? Should birthday member have made this clearer? All of the above?😂
This is long but I still feel I haven't included all info...I'll answer anything required though!