I'm curious, did she end up getting chicken? There are always a few hidden away somewhere unless you're literally the last person being served.

It is unacceptable behaviour, either indicate your preferred choice to the crew early on if the other option isn't acceptable to you (pork if you don't eat pork for religious reasons for instance, or just for personal reasons), or pick a seat near the front. I always sit in the first mini-cabin of Y, seat 19K,20K or 21K typically and never have a problem with first preference.

Being friendly also goes a long way. I've had crew conjur up veg meals for me when the menu didn't have any veg option (when I was younger and was a vegetarian and travelled alone a lot and usually had SPML but on that occasion didn't for some reason). I think it was their crew meal, a nice overcooked pasta.