My partner and I are planning to marry on November 3rd 2019. Yesterday, his mother and sister kicked off because it clashes with his nieces birthday. We picked that date because it’s out of season (cheaper) and works for my parents as they spend the winter abroad. We’ve tried to make suggestions and put a positive spin on things, like suggesting we celebrate her birthday the day before. I’ve also pointed out that it has the advantage that people who would normally not be able to will be able to celebrate Little One’s birthday will be able to as they will already be here for the wedding. But that just won’t do. Apparently, as we don’t have children (they know we may not be able to because of my disability ) we don’t understand. I love his family as if they were my own, but this has really hurt us both. Personally, I don’t see anything wrong with celebrating the birthday the day before. Being 3, I highly doubt she will remember her birthday anyway. I can’t help but feel his sister is behaving like a spoilt brat. Am I justified in feeling like this?