^^ Thank you
I think his is a case of misplaced priorities. A great woman and a great learning opportunity.

Which one should pause first? One is aging(woman) while the other is always available(masters).

One is easy to come by(masters) while the other (great woman )is not

One can open doors to greater opportunities(masters)while the other cannot.( a marriage can dissolve)

Is is possible to kill 2 birds with one stone? so he does not end up losing a good thing altogether?

Op ask yourself this, if she decides to wait for you considering you have invested 4 years into the relationship and that you both love each each other,will you after your masters consider her old for marriage because I truly believe she doesn't mind waiting but the stigma associated with women and age is what must be driving her crazy.
You may need to show her some serious commitment otherwise we shall be reading another story here about a wasted relationship and a 30smthing yr old unmarried lady. If you think age will be an issue later, then you have 2 choices. Allow her to get married to someone else while you pursue your masters.There are plenty of women after all but you may regret having let go a good one.
On the other hand you could still marry and still pursue your masters.People are doing that all over.No big deal.

And after all is said and done dude,your conscience is the right teacher

And good luck

In as much as i don't subscribe to the belief that an Masters degree would guarantee you a job in Nigeria, i believe it would help in self development and expand your knowledge Horizon also placing you on advantage in the labor market especially if you are worth your onions. my candid advice is to get a job, save a lot of money, encourage her to get a job too, do not rush into marriage, u might have reasons to rush out. i don't blame her one bit for the apprehension, she is a woman and must to be considered also.