So, if anyone is still having trouble figuring out favoured foods during dates, let me share some knowledge I've gained from trial and error. (Caveat that this is for v0.3.2 and may be subject to change)
It is possible for a girl to have more than one favourite food. This is not something I considered initially since the first girl I worked on only liked Apple Pie and Beer - but it is entirely possible for a girl to like eating Apple Pie and Ice Cream together (but not always).
Groupings I have observed:
- Meat Lasagna/Spaghetti/Cannelloni/Ravioli
- Meat Lasagna/Pork Dumplings/Pork Ramen
- California/Tuna/Caviar Rolls/Shrimp Ramen/Fish and Salad
-Italian Toast/Veggie Pizza
-Apple Pie/Ice Cream
-Apple Pie
-Cinnamon Rolls
-Vegetable Rolls
I'm not able to confirm that ice cream by itself might also be possible, but I wouldn't rule it out. Still, if you want to reduce your inventory bloat I think you can just keep meat lasagna and a favourite fish dish of your choice in order to cover all options in the first three groupings (assuming they can never come up on their own - my total sample size is only around 30 or so).
And don't forget you can sell back food items at their full purchase price for the time being, so at least for now you can always sell back unneeded food items without repercussion. I imagine that might change once the dev gets proper hint dialogue in to help narrow it down otherwise, but until then utilising these groupings has worked out reasonably well for me.