Don't try and talk her out of it, it will create problems later and will always get thrown back in your face in future arguments.
When things have calmed down tell her although you dont want her to leave you want her to be happy and let her make her own mind up, chances are after a couple of months she may realise the grass isnt always greener and travelling isn't all what its cracked up to be.
When things have calmed down tell her although you dont want her to leave you want her to be happy and let her make her own mind up, chances are after a couple of months she may realise the grass isnt always greener and travelling isn't all what its cracked up to be.