I thought you don't wish to influence her decision to leave sg
for her tertiary education?
Anyway, I think it's alright for her to go and pursue a tertiary
education and meet up with more guys overseas...including getting
her head turned and heart fluttered with guys overseas. -> Why
not take this as a trial in your relationship instead?
Afterall, nothing is constant and even if you eventually manage to
change her mind to study in sg, it doesn't means she won't leave
you for another guy.
Nobody controls anybody, so ultimately if she decides to leave you
in the future, it is always her own choice of decision. Nothing to
do with third-party other than making her feel correct and easier
to break off her current relationship.