Psychological theories about the end of a romantic relationship There's no doubt: many couples break and many marriages break, what happens in these cases?

In the loving encounter brain areas aimed at judgment and critical analysis, are clouded by an increase of dopamine: the neurotransmitter that activates our most irrational and euphoric drives.
The biology tells us that this pleasant situation lasts a few months (activation of oxytocin receptors) because of the decrease of dopamine in the intersynaptic space.

Which other theories could explain the decline in desire/closeness? 

Does exist a split between desire and love?

References:


Massimo Recalcati (2014) "Non è più come prima", Milano: Raffaello Cortina Editore
Michael S. Gazzaniga, Richard B. Ivry, George R. Mangun (2015) Neuroscienze cognitive, Zanichelli.
Is there a split between desire and love?



Of course, love and lust/desire are two completely different things.
A simple definition I have of the word love:  An involuntary response to virtue.

This obviously means I can't "love" someone without knowing whether or not they are honest, benevolent, or have integrity.  It also means that I can't love someone if I am morally corrupt, because doing so would expose my corruption.  To protect myself, I would be repulsed from that person.

Lust, of course, is biologically programmed in our brain and nearly impossible not to experience, unlike love.  I can scarcely be attracted to a woman, go on one date with her, and conclude that I love her.

Like you said, dopamine and other chemicals in the brain can cloud our judgement and lead us to believe we love someone and ignore their red flags for negative behaviors like abuse, when we are merely biologically driven to reproduce with them.  I have heard that this euphoria lasts for about six months until desire fizzles and romantic interest is lost by someone and the relationship ends.

Which other theories explain the decline in closeness?



Abuse of all kinds.  Verbal, physical, and sexual abuse cause big problems, particularly if the abuse is at a young age.  Simply spanking children has been conclusively found to reduce empathy and IQ and increase "brain disorders."  With this information available, more than 80% of American parents still spank their children!  From Christian culture, to Tongan culture, to Muslim culture, spanking and abuse is the norm.  How can we be close to someone if we cannot empathize with them?  Empathy is the deepest level of understanding we can have for someone at any point in time.

I would argue that we are increasingly trying to ignore our unconscious responses to trauma and grief, particularly as children, in society.  The problems are ignored by parents with empathy and emotional distance from their kids which allows them to spank their children and let depression and other problems that could be significant, go unnoticed or even criticized. Endless amounts of "culture propaganda" about how parents are inherently good and loving people despite their abuses, and schools that are teaching kids what to think instead of how to think &amp; solve problems only exacerbate the problem.

Depression and substance abuse is a natural and valid response to events that are usually traumatic - childhood sexual abuse is just one example.  These valid responses in our brain are being labeled with "brain disorder" diagnoses and antidepressants when the unconscious brain is doing exactly what it was designed to do - Warn us that something is wrong.  The benefit for this is obvious.  Just look at the millions of dollars worth of advertising spent for antidepressants on American television.  Often victims are told something is wrong with them, when more often than not, someone wronged them.

Instead of finding the problems in our past that have contributed to unhealthy lifestyle patterns through therapy or self-knowledge work, we, with the help of our "what to think" education, run to the nearest "answer" - a mind-altering drug and a label for our problem.

A closer look at how ignoring the truth can affect society as a whole...

Biologically speaking, as children we are genetically designed to understand that our parents are biologically successful.  They reproduced.  We grow up and learn patterns of behavior from parents in order to be biologically successful based on their success.

Generally speaking:


A boy will model general behavior patterns in his father and be attracted to the general behavior patterns found in his mother
A girl will model general behavior patterns in her mother and be attracted to the general behavioral patterns found in her father


Patterns can be categories such as honesty, empathy, integrity, etc.

For example, children that grow up without a father (exception: children of widowed mothers) experience:


Increased promiscuity
Increased likelihood of committing crimes, violence, and abuse
Increased aggression
Increased teen pregnancies
Increased likelihood of being abused
Increased likelihood of divorce


This is an example of two parents that had an apparent lack of empathy for their children.  It is important to remember that empathy is taught behavior and instead of empathy, they were largely traumatized and abandoned.  The boys absence of a father leads them to have less empathy, shown through crimes and violence against other people.  The pattern often repeats through promiscuity and teen pregnancy and can extend to other families through crime.

I think the evidence suggests that poor parenting choices, whether directly or indirectly, is deteriorating our closeness, community, and ability to love and empathize. How long before the unabused outnumber the abused?  That, I believe, is up to us.

Sources (unfortunately can only do 2 links):

Single Mother Childhood (additional sources)

Facts About Spanking (additional sources)

Search "sins of the father" on the same channel for a firsthand abuse story

Search "confessions of a womanizer" on same channel for a firsthand story from a cheater!

Search "an honest conversation with a single mother" on same channel for a firsthand story from a single mother