My fiancée and I are getting married in fall next year. The location where we will marry has only two available dates and we have to pick one. One of the date is in mid-October where the weather is still not cold and the date numbers have a special meaning to my future wife and myself. The other date is much later in fall, when it's really cold and it's usually very likely that it will snow.
We really want to marry on the first date to avoid the possibility of snowing, to please both our families about not marrying "in winter", etc.
The problem is that the date for the nice weather and special number pattern is also the exact day where my SO's best friend will be 30.
We have spoken to my fiancée's best friend and we have told her that we have a choice and have asked if as of now she has anything already planned, if we could take the date. She's usually not the type of person to organize anything for her birthdays (she never did in the past). This being a sensitive subject, we carefully worded our question so that she doesn't understand it as a request for permission, but rather as an advice scanning. She acknowledged that it wasn't such a request for permission. As expected she said she had no plans and immediately asked her boyfriend who replied he has already something planned on that date for her. We usually are not of the judging type, but given the story of the couple, we have strong indication that the couple won't last until then. We might be wrong, though.
Now, pressed by the location owner, we have decided to take action and chose the date of my SO's best friend's 30th birthday.
How do we tell her (and her boyfriend) that we are going to marry that day without hurting her feelings, without angering her boyfriend and making it clear that they're welcome at our wedding?
Changing the wedding location is just not possible for various reasons (budget, advance payment already paid, size, proximity, type of location, we've been looking for one forever and finally settled on this one, etc.).