Very sorry to hear about this.

On my first F, quite recently, I thought the food and drink were really quite a big step up from club. The attentiveness and responsiveness of the crew (even with a fairly full F cabin) were also a noticeable improvement because of the better crew: pax ratio; not that the CW crew are at all bad. And although I didn't think the seat was a big improvement when I first sat down, it really grew on me that I actually did have room to swing a (small) cat. Plus the view was a lot better.

Sorry, I'm not trying to turn this into a CW vs F thread. But I do think the food is one of the special features of F as distinct from CW, and I think you deserve some decent compensation. How much? Well, did your girlfriend get the equivalent of a CW vegetarian meal? If so, you can hardly argue she should get more than about 10k given that a one-way CW to F upgrade is 25k. But it sounds like she didn't even get that, in which case you might reasonably ask for more, I think. If she got so little food she was left hungry, which might rather ruin the whole flight, then I think quite a lot more is in order.