The year before last he was unwell, with cancer. It was localised, and treated successfully but it defined the year. He is also disabled, with an unrelated condition and is a mobility scooter user.
Every year he has said how lovely it would be to go the the Carols at Kings, in Cambridge. Usually you have to sit around all day to get a ticket but they do keep a few back for those with disabilities etc. So I wrote in, told them about my dad and very luckily got 2 tickets! He and my mum planned to go down to Cambridge, have some late lunch there and make a day of it.
Christmas came and I asked how it was and my mum gushed at how moving and amazing it was, how great the seats were etc. I asked my dad and he said "I didn't want to go in so I listened to it on the radio in the car."
And so it transpires that he decided he didn't fancy it afterall, but drove my mum and brother to Cambridge, dropped them at Kings, and went for a pint. 
My brother is in his 40s, perfectly not disabled, as is my mum.
What the hell was that about? When I said I was hurt, that was my surprise to him and my mum and brother shouldn't have taken those tickets, he said he'd changed his mind and it was up to him who he gave them to, and I was being silly.
It's shitty though isn't it?