Your man is a typical man - in short, he doesn't
relate emotionally. But the matter of the fact is that he still
feels like flesh and blood. Every action, there will be a reaction
- therefore the explosion of suppressed emotions is but an
eventually event which will occur when the right catalysis is
given.
This catalysis can be anything - from infidelity to plain
enlightenment/resolution.
To fuel the flame; you are oblivion to the fact that there are
dissatisfaction in your relationship. Your man could accept the
notion of your individualistic nature, but his acceptance cannot be
transformed into prerogative for your wilfulness.
This will in turn churn dissatisfaction and when it is not
resolved, you will have tremendous difficulty to eliminate this
deep seated frustration that have already take roots in his
soul.
No doubt, he is also partially at fault for his ineffective
communication to convey this suppressed thoughts and feelings to
you regularly prior before this outburst.
You may want to consider the following
points:
I) Throughout this nine years, both of you have enjoyed the
stability this relationship has been offering, but this stability has also
adversely caused your relationship to have this gradual shift of
mindset/attitude - where you both turn on 'auto pilot' mode and
allowing your relationship to cruise at ease.
Nine years and almost a decade! What could ever happen? 
If only life was logical, the above statement would have been
perfect. But such ideology only exist in utopia. Without constantly
having to protect, fight and nurture your relationship, your
relationship will also wither and perish from 'malnutrition' and
mistreatment. In fact, the longer your relationship, the harder you
have to slog to prevent yourself from cruising into auto mode
because we do not experience as much growth to 'reward' ourselves.
If your growth was charted on a line chart, the curve will be
gradual and not steep (the steep growth represented honey-mood
period and all those sweet past).
II) Individualistic nature is great for personal growth, but more
often than not, it is malicious to Love. Because relationship calls
for the quality of mutual, while individualism seek for solitary
movement. It is heartening that you show willingness to change, but
I am not too sure if it is just a temporal measure to retain your
relationship or real desire of wanting wisdom to evolve
yourself.
As for your man; I am not too sure if it was indeed an ultimatum he
has presented to you, or just a prelude to a break up.
I guess you may want that precious chance to give it a decent shot
to work on yourself/relationship, but he must truly give you that
chance to attempt as well. No point trying to do
something here, while your man has already decided subconsciously
that he wants out.
III) Trying to work on your personality alone is like trying to dye
hair yourself. You may somehow get it done, but you will create a
mess or the result may turn out to be different. My advice is never
attempt this alone - include him into your evolution to be a better
girlfriend because only he knows what he wants to see in
you. He also has to learn to communicate and share about
his perception/views about your hidden flaws so that you could,
simultaneously, challenge those blind spot of yours and
improve.
In summary:
- Understand that effective couple communication is your only tool
of survival for a long relationship like yours. And if marriage is
part of your agenda, the more you two should begin learning how to
do it... based on your own relationship... your own Love.
- Abandon individualism and adopt mutual thinking (Reduce influence
of Uranus and embrace influence of Venus). Learn that our
personality evolve periodically. It is so much easier to say 'I am
like that and he has to accept the way I am', than one trying to
compromise and adapt, so as to reduce the friction from personality
differences.
It will probably take some time. A LONG TIME in fact. Don't get
discourage by pebbles thrown into your path for trying to revive
this relationship because the things are intense now. Ironically, people are always
doing the same thing while expecting different
result. You cannot allow yourself to such thinking
if you want to prevent your relationship from drowning.
You may succeed, but you must go beyond succeeding this
revolution must be substantial to remain, influence and carry on.

Cheers