Was meant to go and stay with dsis for the weekend.
Think she expected me to come fri night until mon morning but have found out I have interview for a voluntary position on the Saturday, which I am reluctant to miss.
She seemed a bit upset when I spoke to her about it and said I could now only come on sat eve until mon morn. Also arranged to meet a friend while in the area.
I know weekends are precious to her and her dp so purposely tried not to stay whole weekend. Has massively backfired though, I've upset her and feel awful 
How can I make it better?