[My first post on this thread too.]
I have it slightly differently from most people on this forum, because I know what it's like from both sides (I'm a supporter and I have PTSD).
I also read an amount of prejudice into your postings - I'm sorry if that isn't there, or isn't your intention, but generalisations about a whole group of people can come across as little else.
At the same time I also wonder if you've dealt with your own trauma as well as you appear to think you have. While it won't cause PTSD for everybody, trauma takes a toll on everybody. Denying that fact can be part of the defence against it, and attacking those who freely admit they're traumatised can be a form of denial (as put much more eloquently by the above poster). You talk about bullying, but surely, you must have known that talking in the way you were was going to draw a bad reaction from some of the readers.
I have to admit that I can't see why you're posting to a forum for supporters and sufferers of PTSD, given that you aren't, in reality, either. I wouldn't go so far as to suggest you shouldn't be here - you may have conflicted emotions yourself about walking away - it just doesn't make sense to me.
I actually don't think it's unreasonable, or unfair to expect others to care about our personal issues. I think it would be unfair to expect a stranger on the street to - but not to expect it from a loved one or a friend. But I also wouldn't think it unfair or unreasonable for them to expect you to care about their personal issues (whether you have PTSD or not).
When my husband was diagnosed with PTSD, (I won't say 'got PTSD', because I think he's had it as long as I've known him), my initial reaction was to run in terror, after I read about what it was. After the shock wore off, I effectively rolled up my sleeves, buckled down and thought 'right, lets get through this'.
I'm not saying that this is any better a thing to do than walking away - that's a decision everybody has to make for themselves, and I'm not going to castigate anybody who does walk away. I chose not to. I probably had no idea at the time how hard it was going to be, but I kept with it. Yes, it hurt, yes, it was deeply, deeply upsetting, and yes, there were plenty of times that I wanted to leave, or throw him out the window! ;) But we got through things, he worked very very hard, and it's much better now.
It was probably easier for me than many, because despite having combat PTSD, the time when he was in too much pain to show me he cared came in short bursts, rather than prolonged spells.
On the question of 'do sufferers make their loved ones suffer' - well, yes, in a way they do, and it's unavoidable, because their loved ones will have a very hard time dealing with the pain they're seeing, and the reactions they're faced with. Supporters also tend to get less acknowledgement from the world at large - I know I encountered a lot of 'he's ill, what's your excuse' attitudes when things got rough (I still do). But I think that sufferers from other illnesses cause their loved ones to suffer - if you get cancer, or dementia, or motor neurone disease, you can bet your loved ones are going to go through hell. Does the fact that it's a mental illness / injury make it somehow different??
In answer to the question of 'why don't people empathise / understand'...
I think that people can't empathise unless they've been through something similar - I think with PTSD that means not just having the initial trauma, but the reaction to it, too.
As to understanding, I think that until you come into contact with it, PTSD is still fairly unknown. People may have heard the term, seen it on the news, etc, but think of it as being like depression (not to belittle depression, which can be life threatening in itself). People don't realise that it's depression and a dozen other things all rolled up in one neat package. Or that it's mostly life long. Or that the most seemingly random things can trigger it.
When hub first became unwell, the most helpful thing I read was a piece on (I think, it was years ago) the Combat Stress website, saying that as a partner, you shouldn't tell the sufferer that you understand what they're going through, because unless you had PTSD yourself, you couldn't possibly. I was always very careful to make that distinction. As it turned out, having now been diagnose with PTSD myself (unrelated to his and going back to childhood) I really did understand what he was going through. A friend thinks that may have made it easier for me to not take offence, or not take it to heart when he was very poorly, and pushing me away, trying to force me to leave him, etc, but to understand that it was coming from his pain, not his deliberate intent to hurt me.
I also think that many people genuinely do think they understand. I think they think they know what you're going through, and just don't realise that they are almost completely unaware of it. Obviously, you can't go around with a manual for everybody around you to read, so that's something that we as sufferers have to learn to deal with, and maybe not take offence at, in the way that we hope those around us won't take offence at some of our reactions.
Mind you, I'm quite open and honest about both of our illnesses. A bit more guarded with hub, because he's a bit more careful about who knows, but about myself, I prefer to be open about it because it just makes things simpler. It also makes it easier to explain things to people, and to apologise when I stuff up and get shouty or walk away if they know in advance...