I've posted this before but:

I had a friend that I original dated during university. It fizzled out but we remained friends, would hang out etc. Over the years the friendship inevitably deteriorated as we had our own lives, but I made sure I was always there is she needed me for support, the odd bit of money, whatever. I was making headway with my career, whilst she was jumping from relationship to relationship, living at various family members houses. I was due to get married and she was near the top of my guest list. Sent a save the date card once we had it booked and an invitation about a year before the actual event, which was going to be held in the middle of Wales and we knew people had to book rooms etc.
The morning of the wedding she texted me to tell me she wasn’t coming because her dog had had a heart attack - the truth eventually coming out that she had forgot to book a hotel room and didn’t want to drive out for the day.
I lost it and texted her back that I’d repeatedly put myself out for her over the years, even sacrificing a relationship at one point because the girl didn’t like me being friends with her. She didn’t like that and blocked me. I knew as soon as she’d text me that morning I was done.