I have to agree that it is annoying to have your date yak away on the phone while you're out.
Basically, it's the same,how some women feel , after a long day at work,their husbands/bf end up being stuck to the TV and remote control all the time while their wives/gfs try to have conversations with them.No one likes being ignored
It's an Asian thing, because we are not aware of such 'etiquettes'. It would be good to voice it out
Afterall, being together is a learning experience.