Sadly, I have also experienced what you describe, bpcyclist. Not by my immediate family members, but many others.

There are some times I wonder if they don't reply or reach out because of their own life stresses and responsibilities, because I now seem so different than them (no children vs. them being hyperfocused on theirs, and I'm on disability, while they work), or because I had "fallen off the map" for long enough that they moved on from me. Out of sight, out of mind. But beyond that, I know people have shut their doors, figuratively, to me because of past manic and mixed manic behavior. It can seem scary to some people (odd behavior, weird anxiety issues, psychosis), or is just too overwhelming. Such behavior can severely anger or disappoint people, and as you discussed in another thread, people hold grudges and don't forgive. Sometimes understandably, but other times not so much. And then there is depression. People have their limits to being around that!

Another factor was the period when my illness became so mentally overwhelming for me that it dominated my life, excessively. Yes, being in and out of the hospitals and IOPs and in therapy all of the time was part of it (just plain being extremely sick), but it went beyond that. Many people with bipolar disorder, especially when first diagnosed, begin to think the illness is their life. That they ARE bipolar, as opposed to HAVE bipolar disorder. I was guilty of that for a handful of years, and it's understandable. It was an obsession, of sorts. I had seemingly lost key aspects of my old self. I had forgotten who I really was...beyond bipolar disorder. I had convinced myself that bipolar disorder was all I ever was, which wasn't true. This has changed. Memories returned, as well as mental clarity because of healing and therapeutic work. I have even grown into a new me, of sorts. A better me, I think. I see that as a beautiful step, and have met many new people along the way who see me as the NOW me. Unfortunately, some from the past don't or won't. It is sad...the death of what was. I grieved. I moved on.

A couple of add-ons:

I know that experiences differ, but when I was hospitalized for psychiatric reasons, my husband was my one and only visitor. All 10 times! There were no "get well" cards sent to me from work colleagues or friends. Definitely no fruit baskets! Neither of my siblings sent well wishes. When my husband called my father to inform him of my hospitalizations, my dad always said "Tell her to call me when she gets out." I suppose some of this is understandable (or my family's attitude), and sometimes I wouldn't have wanted other visitors (e.g. when psychotic). But imagine if I had been hospitalized for a heart attack? Or something similar?

Bipolar hypomania/mania can certainly make a person exuberant and attractive, but just as it scares away friends, it certainly deters potential new ones. I experienced all three since my illness started. In my case, I developed a "Teflon" shield, of sorts. You don't want to like me? Fine. Whatever! You won't forgive, despite my apologies? Whatever! The problem with this was my lack of insight into my illness, in early years. I came to believe that my behavior that caused those reactions was inevitable, and sometimes even justified. Perhaps I could cry about the relationship issues, or say "Who gives a damn!" Trouble was, it got really bad over time. I had to accept/learn what was going on. I had to seek treatment. I had to work on insight. It was my responsibility to do so, or continue to experience consequences.

bpcyclist, perhaps the last two paragraphs are not relevant to you, but may be to others.I believe they are on topic.