The
moment when you knew your days were numbered - your mind is still
thinking about her. Brandishing such deep affections, why do want
to bereave yourself and her from revelling in those final, precious
moments together? By being an escapist, you not only resign to your
fate of an impending doom, but also, you have subconsciously
planted a seed of guilt into her life.
Do you seriously think that by accepting option II, you could free
her from this relationship easily to another love? In fact, when
she realised the REAL reason why you ditch the relationship, the
truth would probably torment her for the rest of her life and how
do you think it would affect her future relationship?
Selfish I say!
You are NOT dying unless you gave yourself up! At this current
stage in life, who cares about what the doctors say?
Does Doctors = God? They can forecast your remaining life, but do
they have the final say?
There are people who survived through health crisis, despite
certified death cases, or even having longer life expectancy simply
because of sheer willpower. You don't have to be delusional about
your situation; accept the reality that your body is weak and may
cease to function, but as long as you still breathe the air around
you and have all your senses working, you earn another day to
create values and meaning to those around you.
So what if you have brain tumour - does that make you demented and
lose the ability to love?
If her presence in your life is so important, then you must fight
to earn everyday of your life for your stay on Earth. Everyday
lived is everyday gained.
You have absolutely nothing to lose my friend.
Every man will
die, but not every man truly lived; you will be in
my prayers. 
Cheers
