Tell the girls you're talking to about this problem. They may take pity on you and lick your lips. Long shot though.
Licking your lips will make your lips more dry, as the saliva will take the moisture from your lips.
Try your hardest to kick the habit of licking your lips, and use something that isn't petroleum based (vaseline is one) for your lips.
Just use a chapstick or lipbalm, since these two are not messy and are easy to apply during the day when you need to. And if your friends ask why you're using lipbalm on your lips, just tell them the truth, that your lips get very dry when you talk to them (it might sound silly when/if you do, but they won't care that much about it).
My lips also go dry whenever i see my boyfriend.why does this really happen??
My lips too get dry over time whenever I see a girl :|