There is a fasinating article in The Independent summarizing much of Dr Helen Fisher's work related to Love and its neural basis as well as many other aspects of Love. As per Dr. fisher Love comprises of three systems: Lust, Romance and Attachment.
Lust is a craving for sexual gratification, which you can feel for a whole range of people.
Those caught up in romantic love focus all their attention on the object of their affection. Not only do they crave them, but they are highly motivated to win them, they obsessively think about them and become extremely sexually possessive.During this state the brain is driven by dopamine, a neurotransmitter central to the reward system.
The third brain system is attachment - that sense of calm and security you can feel for a long-term partner. It is associated with the hormones vasopressin and oxytocin, which are probably responsible for the sense of peacefulness and unity felt after having sex. Holding hands also drives up oxytocin levels, as does looking deeply into your loved one's eyes, massage, and simply sitting next to them.
As I am prone to using analogical thinking to extremes, this seems to me like the 3 memory systems that have recently been discovered- one for novelty detection, the other for familiarity detection and the third for recollection. Lust to me mirrors the novelty drive: craving for new partners or new and unusual sexual experiences with the same partner. Romantic love is all about feeling a special bond with one (or more) person and being in special resonance with them to the exclusion of everything else. It leads to much more lasting recollections that do behaviors triggered by Lust or Attachment. The Attachment love is actually the long-term commitment and trust triggered by being vulnerable to a familiar person and involves the generational of feelings of familiarity/trust etc amongst long-term couples.
While the evolutionary rationale for Lust -having sex with as many new individuals as possible- is clear in that it distally takes care of the need to procreate and spread one's genes around; and the evolutionary rationale for Attachment is also clear - the long-term pair bonding ensures that the need of children's would be taken care of and both parents would do the parental investment- the evolutionary rationale for Romantic love is not that clear. If one looks at the costs associated with this, then the mystery appears to be more depended. Dr fishes offers a very plausible explanation- that romantic love is to ensure we are monogamous and our mating choice is restricted in the crucial young ages to one person.
Scientists have discovered that certain parts of the brain become deactivated when we're in love, including areas linked with negative emotions, planning, critical social assessment, the evaluation of trustworthiness and fear.
Biological studies have found that this phase of reduced cognitive function, during which faults are ignored, can last from one to two and a half years. This temporary state of delusion has a vital human function. If we immediately saw all our partner's faults, we would be less likely to form a stable relationship in which to produce children.
And it is just as well that it is short-lived: romantic love is has an enormous metabolic cost. "I think romantic love evolved to enable people to focus their mating energy onto just one person at a time, thereby conserving mating time and energy," says Dr Fisher. "It's not conducive to real life to live in this state for 20 years because you're distracted by it, you can't think of other things, you forget what you are doing, you probably don't eat properly, you certainly don't sleep well and you go through highs and lows."
To me the dopamine connection of romantic love seems very intriguing and hard to swallow!!