Don makes a very good point about the capacity for emotional intimacy of those with bipolar illness. It is clear that someone who is in the throes of either the manic or the depressed phase of the illness is in no condition to relate well to others. Even though such decreased ability to relate to others is by no means limited to bipolar illnesses, it is instructive to think about the mechanism as it relates to bipolar disorder, particularly the manic phase.
As Don has already stated, he has extended the constructs of affect theory to suggest that a person in the manic phase of bipolar disorder has a biochemical glitch that is continually triggering the affect interest-excitement, and at a very high level of intensity. Tomkins postulates that interest-excitement is usually triggered by stimuli that are novel, whether these stimuli originate outside of the person or as thoughts, ideas, etc. inside the person. Because the person who is manic has an interest-excitement mechanism that is locked in the "on" position, she or he finds almost everything to be novel. Since it is affect that directs conscious awareness of the world around and inside of us, a person in a manic state has the problem that their attention is either intensely over-focused on something that may or may not be still be novel or constantly being drawn from one "novel" thing to another, often in very rapid succession. This can make it difficult for another to communicate with them because their train of thought is either stuck on something or jumping from one topic to another too rapidly.
I have defined emotional intimacy an interaffective process between two people where the inmost parts of the self are communicated to the one another by tangible displays of affect. Such communication depends upon the ability of each partner to be able to open up the inmost self to the other in order to both exhibit what is going on inside the self and learn what is going on inside of the other. It is very difficult, therefore, to be intimate with someone who is constantly either locked onto something or distracted by other stimuli because they cannot learn what is going on inside of the other and the other cannot follow what is going on inside of them. In other words, any smooth flow to interaffectivity is blocked because when manic, a person’s capacity for intimacy is significantly diminished by the biologic illness.
In the specific case of someone who has too much interest-excitement being triggered by a biologic phenomenon, one may initially feel great interest because that person seems so very interested in them. But after a while one discerns that that interest is mostly independent of anything one does or says, or is too easily distracted by other things or people. This blocks one’s interest and triggers a shame reaction, causing that person to feel rejected, isolated, hurt, and distanced from the other.
My clinical experience with couples where one partner has bipolar disorder is somewhat different than Don’s. Since I am identified as a couples therapist, I am more likely to be referred the couple rather than just one partner. By the time I see such a couple, if the person with bipolar disorder has had a number of serious recurrences of the illness, the non-bipolar partner is usually feeling very rejected and angry. Where once they felt great interest toward and from the other, now they feel too much impediment to that interest. They have often begun to protect the self by diminishing their interest in the bipolar partner.
Sometimes direct explanations about the nature of the illness and how interest-excitement is too great, then too low due to a biological glitch can be very helpful in reassuring both partners that what they have been feeling is real and has a cause that can be treated. (Such explanations can be very clear if the mental health professional understands affect theory.) However, sometimes it is too late, and much too often in my experience, the non-bipolar person has retreated so far from the other that they have fallen out of love and no longer wish to continue the relationship. Although a well-trained clinician can spot bipolar disorder easily, I long for the day when we develop the means to determine whether someone has an illness such as bipolar disorder by blood test or some other simple test. I believe that such a test will be performed routinely by pediatricians and general practitioners. And I am sure that when this happens, we will save a lot of perfectly good relationships by more timely and hence more effective treatment.