Family drama!!!!!!

There's really nothing you can do. She probably can't change her date without a significant loss. It pretty much is first come first serve. Sorry, hope you can find another date that you love.

Since you don't have a venue yet then you could easily pick a different date. Until you have a venue secured then the date is fluid and not guaranteed. A lot of people have had to postpone their weddings so finding a venue could be very difficult especially if you have a set date in mind.

Until you have a venue, you don't have a date. You never had that date, just something you had in mind. In this case, I think you need to pick a new date, but remember that you don't have a date until you have a venue. Venue shopping should be priority one for you.

Did the cousin know you had this date in mind? Or was it unknown? If they’ve already reserved a venue and what have you, and it sounds like you haven’t yet, I would be flexible and move your date.

I'm so sorry; it can be so upsetting once you get something set in your head but it doesn't work out in reality. Unfortunately, though, it seems like you don't have anything actually set for that date, so there's nothing to do about it. If they booked a venue, they can't change the date without a loss, so the polite thing to do would be to find a new date when you do find a wedding. Also, if you want a spring 2021 wedding, you'll probably have trouble finding your perfect date anyways since it's less than 1 year away during a high-demand season and so many people have had to reschedule to 2021. You may need to book soon, even with this issue aside.

I agree with others that you don't really have a date until you have a venue booked. I have seen so many couple here have trouble finding a venue that works if they get a date set in their mind first. It's so much easier to pick a general time of year, then choose a venue, then book a date they have available.

So, as for what you should do now, you definitely should NOT contact this cousin with whom you have no relationship with and ask her to change her date. You should just continue your planning, prioritizing booking a venue as soon as possible. Before you sign the contact for a date, make sure to check with your VIPs (the people you cannot imagine getting married without) to make sure they are available on that date.

Unfortunately the only way to secure the date is to book a venue for the date intended. It was sucky, if she knew it was the date you wanted for yourself. Since you don't have the best relationship how did she know that you wanted that date? Or was it literally just a coincidence that she chose May 15th? As if Spring was not already the busiest season, you'd only have as of right now 9 month's to find, love and secure a venue during the busiest season of the year during a pandemic. I understand its not what you might want to hear but you I wish you the best in finding the best venue and date for your wedding.