Wedding guests no show

I've known my friend and her partner for over 10 years although we haven't had much cotact apart from the occasional Facebook message for the past few years. Despite this I invited them both to my wedding at a cost f £60 per head and they said they would be attending right up until the day before. However on the day of the wedding they didn't show. The wedding was at 2pm and they messaged on FB at 4pm to say they had tried to make the journey but had to turn back. My friend suffers from arthritis and apparently the pain got so bad during the journey that they couldn't continue. I feel that if my friend knew that her illness sometimes stops her from dong things then she shouldn't have comitted to coming in the first place as she knew it was costed on a per head basis, Secondly she shouldv'e let us know before 4pm and she could at least have sent a card or something after the event. If she had declined in the first place I would've understood and it would have saved £120. Am I right to be upset with her? I did attend her wedding a few years back.