I am going to be
truthful here:
To pursue a LDR for an estimated four years is a dangerous feat for
any relationship. It is high risk and represents an unstable model,
unless you two are mentally and emotionally tuned to accept those
challenges. And I mean real tuning.
Here's a sad truth: MOST LDR fails.
Not to overly douse you with cold water; the reason why LDR fail is
largely because people are using conventional relationship methods
to handle LDR (and yours begin from a conventional relationship).
They perceive similar standards, needs, methods, wants, desire, etc
of a conventional relationship and applied them into LDR.
Obviously when you are not feeling too good emotionally, your bf
can't be there for you. Obviously when someone is chasing you, your
bf cannot be there to deny his competitor with his presence and the
list goes on. People engaging in LDR gradually give in to such
vulnerability and in turn, reconsider their relationship, which is
why most LDR fails. If you want to accept LDR, you got to truly
give and expect nothing in return.
Somewhat like God? You pray to him, but God don't appear to you
directly (maybe in your dreams perhaps). You lived on blind faith
and believe in him until circumstances make you lose track of that
vision.
If you want to accept LDR (especially those more than 1.5 years),
you got to have a drastic change of mindset and also a change of
lifestyle. All the lovely thingy that is granted to you this 5 1/2
years, will likely, NOT happen meanwhile. When I talk about those
lovely thingy, it's all those insignificant thingy, which
you never knew it
mattered, but when he's gone, you will gradually come to an
understanding that it actually matters and make a difference in
your relationship.
All those insignificant thingy: e.g. like your bf used to wake you
up for work through a telephone call, so as to ensure that you go
to work on time. After he's gone, you find yourself being late for
work because the phone never rings.
Your bf used to peel those oranges, so that you could eat them.
After he's gone, you never touch those oranges because nobody peels
them for you.
Know what I mean? People become vulnerable because they long for
the 'previous' sort of lifestyle they are so familiar with and this
creates instability. They are using the old ways of expectation and
methods of doing things to a 'new' sort of relationship.
You will probably need:
I) Lots of blind faith.
II) Lots of drastic changes.
III) Lots of giving and zero receiving.
And lastly, probably no sex (if you have been leading a sexually
active life).
P.S: Better to understand how challenging this route is and not
delude ourselves, thinking that
we-have-been-through-many-thingy-and-we-will-also-surmount-this-difficulty
sort of mindset, so that you can better prepare yourself
emotionally and psychologically and not succumb to circumstances
while leading a LDR. It is difficult and even when you succeeded in
maintaining LDR for four years, it is not exactly fulfilling as
well. You will probably feel relieve, more than fulfilment in fact.

Cheers