My DW invited her mother around for Easter Sunday dinner tomorrow and she accepted week ago.
This evening she calls and says she has another offer with DW's sister and her son and girlfriend who she has never met, but never mind, she will come to us.
DW was happy because she has gone to a lot of bother over the dinner already but felt really guilty and suggested that MIL should go to meet the new GF.
My view is that MIL only called to alleviate her guilt. If she was going to come to us she would have done so anyway and there would have been no need for the call. Just more evidence that she is not the sweet old biddy she makes herself out to be!