And if you're giving cake as a gift, which I often do, then great! In lieu of a gift of similar value, I'll give you whatever flavour you'd like. And I'd ask for my favourite in that case as well.
But all of the other gifts will be for the exclusive use of the birthday boy/girl - the cake is for sharing at the party, and especially at as small a party as this, it seems ungracious that s/he should insist on a flavour that they know one of the guests doesn't like, and especially ask to be baked by the guest who doesn't like it.
CakeEater (oh the irony of that name in this thread!) has mostly articulated what I had tried to ask earlier. That it seems ungracious to ask for a flavor that 1 of only 4 people doesn't like, especially since the one who dislikes is the one purchasing. However, I think the part creating the doubt is that while the cake was for sharing, it was also intended/interpreted as a gift, which I think we agree, that as a gift, the cake should be the chosen flavor.
I would not call Adam picky about cake, but more that local groceries only have a few staples. There's usually chocolate, vanilla, German chocolate, coconut, carrot and red velvet. No one likes German chocolate and half don't like the cream cheese frosting on carrot/red velvet. Vanilla is painfully boring/bland, even if there's coconut on it. I'm not sure why, but vanilla seems to be a drier cake than others around here.
Which is why Adam tried to open the door to pie options, because he enjoys a few cream pies and even several fruit pies.
But just opening the door to cake mixes, Adam likes spice, orange, and strawberry, all of which are perfectly fine flavors for all 4 people involved. When Adam would make his own cake, usually it'd just be a box mix in a 9x13 pan with no frosting, so you know.. not the pinnacle of difficulty here. The last couple of years, he's been playing around with tiers and icing, but he's still perfectly happy with a plain, non-frosted cake. I think it somewhat bugs Adam that while Jackie is capable of baking a cake and has done so many times, that she wouldn't/couldn't do so now, because then there wouldn't have been an issue. Orange cake (or whatever) would have been perfectly fine.
And for those looking for clarification if there was cake; No, ultimately there was no cake produced. There's a seasonal cake that shows up over the summer, a plain cake with buttercream frosting and glazed strawberries on top. Adam suggested that one, if it was available, but knew that it might not be, Jackie would just have to check the grocery. He had assumed that she would tell him if it was not available and start this mess again, but she did not and no cake ever came. So, he doesn't know if there wasn't a cake available so she decided to do nothing or if she just completely flaked on it. There's a faint sliver of chance that perhaps a cake will appear when his preordered item/gift arrives sometime this month, but he's not holding his breath over the cake OR the item, because he's realizing that Jackie is apparently one of those "it's the thought that counts" people, where they say things, but don't necessarily follow through with doing