Bismarck didn't let Apple Spice join his circle of friends because of a few reasons. But after getting a small bit of perspective on Apple Spice, he goes off to apologize to her, and then learns more about her then he would have ever thought
Apple Spice got a card from Lightning asking her to be is special somepony. She wants to accept and wants to love him but there is one problem. There is one thing preventing her. She knows that she is going to outlive him.