Differentiation is the development of a self and involves two basic life forces.    
                                    
Differentiation is the drive for individuality and the drive for togetherness. Differentiation is the process and develops throughout a lifetime. The key is to not hold grudges and to recover quickly from arguments, to tolerate intense intimacy and maintain your priorities in the midst of daily life.  It lets you expand your sexual relationship and rekindle desire and passion in marriage.  It is the pathway to the hottest and most loving sex you will ever have with your spouse. 

Differentiation brings tenderness, generosity and compassion -- all the traits of good marriages. 

When two life forces for individuality and togetherness are expressed in balanced and healthy ways, the result is a meaningful relationship that does not deteriorate into emotional fusion. 

Well differentiated people can agree or disagree without the fear of losing themselves
and still “know who they are.”

They do not have to leave the situation to hold on to themselves.

What is so common in society are the “fusion fantasies” which become the source of marital discord.
The illusion that good marriage partners are like tightly choreographed figure skaters is an impossible way to live. Those individuals, who are fused, become controlled by their connection. 
They then lose their ability to direct themselves and get swept up in how people around them are feeling. There is room for one opinion, one position. 

Differentiation is the ability to stay in connection without being consumed by the other person.
Our urge for togetherness and our capacity to care
drives us to seek connection but true interdependence requires emotionally distinct people.

Emotional fusion is the opposite of differentiation. 

Fusion is an invisible but tenacious emotional connection. 
Notice that differentiation is neither connection nor lack of connection—it is a different kind of connection.  It is not individuality or independence.  It is a sense of self and a higher order process that involves balancing both connection and autonomy.

Emotional fusion is connection without individuality.

Lack of differentiation alienates us from those we love. 
Emotional fusion deceives us into thinking that we are not connected and we move away in defense.

The deeper truth is that we have to move away to counterbalance the tremendous impact we feel our spouse has on us.  Or, unable to turn away, we turn ourselves over to the connection, but the partner feels engulfed and emotional distance is created.

Declaring boundaries is an important first step in differentiation. Highly differentiated people also behave differently than being autonomous and independent.  They can be helpful of their impact on others and take their partners’ needs and priorities into account.  The sense of identity develops slowly.  From the aspect of differentiation develops mutuality. 

Differentiation is the key to mutuality, a perspective, a mindset; it offers a solution to the central struggle of any long term relationship going forward with your own self-development while being concerned with your partner’s happiness however not taking responsibility for that well being. 

• Part of marriage’s elegance is that spouses always make ideal sparing partners.  If you and your partner argue over whom is healthier or more evolved know this.

 

• You have about the same tolerance for intimacy, although you may express it differently. You and your spouse make splendid sparring partners because you have roughly the same amount of differentiation.

 

• Assume you are “emotional equals” even if you would like to believe otherwise. If you want to discover important but difficult truths hiding in your marriage, stop assuming you are more differentiated than your partner.  Look at things from the view that you are at the same level and you will soon see the trade-offs in your relationship.

Taken from Passionate Marriage - David Schnarch, Ph.D.

Virginia Satir, a well known psychotherapist writes about
 "channels"
our means of deep listening and communication and feeling heard.
 
I have spoken about the most desirable physical condition
to accomplish congruence --
being at arms length and eyes level, sitting or standing.

eyes / seeing one another
ears / hearing one another
mouth / talking
skin / touching
nose / smelling

If you look at me and I look at you, then we can see each other.
Otherwise we have to make it up.
We can think about these new channels as tubes that are
moving things back and forth between people,
like the ears do it through the airwaves.

If all my channels are working,
my sight, my sound, my touch, my smell, my brain and my gut
are all connected,
they are all open and I hear something full and round.

The muddy picture comes when someone is talking here and looking over there,
or when somebody is talking to somebody and thinking about something else.
It is the equivalent of one radio receiver
in one ear and one in the other with each turned to a different station.
That leaves the opportunity for people to feel
mis-heard, mis-seen, mis-felt,
all the consequences that lead to
mis-contact.

Many people use mis-communication
as an occasion to blame either themselves or the other.
What I suggest is that this be used as a clue
that the channels are not connecting
and go on a search to understand
what is happening instead of blaming,
which will surely stop any further discovery.

When making such a search, ask yourself the question,
"What did I see and hear, and what thoughts and feelings did I then have?"
Share this with the other person and ask that person to do likewise.

Your chances of really being seen and heard increase
when you take responsibility for having yourself at arm's length position
with anyone (including children) with whom you are trying to make contact.