It is rude to blow off a friend's birthday.
Samantha was looking to buy tickets to a concert on Friday, but Samantha had already accepted Christine's invitation to her birthday party that same day.
Samantha wants to go to the concert.
Samantha looks for other concert dates and invites Christine to go the concert the following week as a birthday gift.
Samantha skips Christine's birthday party, and tells Christine she'd rather go to a concert than her party.
Samantha has a great time at Christine's birthday party and the two get to bond in the concert too.
Christine gets mad at Samantha and the two friends stop talking to each other.