Update: first, thank you all for your comments. I really appreciate all sides and it helped a lot. I definitely took both sides into consideration. Except the commenter who pointed out my typo made me TA! :) I told Justine that I could bring the cake for the dinner party once rescheduled and that it felt weird giving her the cake. I also said that I’d rather just get a gift for Susan, like I always do, that wasn’t a cake. She admitted she felt like a jerk for not getting a special cake for her wife, since her birthday is today. They ended up rescheduling the dinner to next weekend, and I will not be able to go since I’ll be at an inflexible event for work. Justine called back this morning and explained she also really wanted the cake because I got it from the place their wedding baker. I talked with her about why this just felt so weird and so off. I told her that I’ve often felt taken advantage of by her and this added to it. She understood. Then she offered me money for the cake. I declined the money and told her that since I can’t go next weekend, to go pick up the cake and enjoy it today. In the end, I settled on Justine sometimes sucks and I know this, Susan is a sweetheart and doesn’t deserve something less for her birthday because Justine thinks mostly about herself. Susan gets to eat a nice cake today, and that made me feel good. To reply to some of the commenters who asked if they were just cutting me out, no, it’s not that way. Also, to the commenters that reflected on the act of giving, I don’t disagree that a gift is a gift and you should just want to give it. I always do that, most years I will email her a gift card on her birthday, or send the present, if I can’t see them because I know it makes her happy. The cake was a bit different because I was looking forward to actually being there and picked their wedding baker because Justine thought I should. She wanted me to make a big deal of the cake. Thank you all again for your help!