Sisu,
Again, your experience is not uncommon. That in itself is a relief I'm sure!
My ex and I were in a fabulous relationship for 4 months before it started to rear it's ugly head. I'd speculatated that he had some sort of trauma from his 2 tours in Iraq, primarily because of how distant he sounded when he spoke of what he went thru. When we met, he was still active duty, and was set to be discharged to inactive in a few months. Unfortunately, I'd made plans to move up to New England before meeting him. So, we only had about 2 months together. Things went well for the next two months, although I did noticed slight changes. I'd attributed it to the difficulty of a long distance relationship. Then, on one of my visits he had a crazy, angry outburst and threw a shopping cart across a walmart parking lot for no good reason. That was the beginning of the end. Shortly thereafter, I broke up with him. I just couldn't take dealing with someone who was contantly on edge.
We've been in contact on and off for the past two years. Trying to resume where were were, but it just wasn't right. I'd see those fragments of happiness that were ever-present the first few months of our relationship come back out again, and it gave me hope. This past holiday season we got back together. He said he's been receiving treatment (well, meds only) for a few months (the drs originally thought he just had an anxiety disorder), and was happy again. He said he's changed and really wanted to be happy with me. And onto the rollercoaster I hopped...all over again.
He was great for close to two months. Better than ever. He was more sensitive because of this new self-awareness. But, then he gradually pulled back again. Stress at work, financial issues, and probably the strain of trying to maintain a long distance relationship was just too much. I'd try to address the changes with us. He'd deny or ignore. Until finally, he just stopped trying to communicate altogether.
Sorry for the novel. But, I felt the details needed to be conveyed so that you could see the pattern for yourself. I feel that he's had ptsd for quite some time, but it appears to be boiling more and more to a head. His ability to behave "normal" (if there is such a thing) is decreasing. I also feel that it didn't become truly full blown until he left the service because he had the safety of knowing that the little things would be taken care of. But, life's responsibilities (rent, job, relationships) get too much some times, and one thing - like a needed car repair- can toss them over the edge.
If not receiving intensive therapy and treatment, I have no doubt my ex could eventually be of serious damage to himself or others. I believe this to be the case with all (chronic) suffers too. Meds only mask the problem, letting him think that he's managing just fine, and doesn't need therapy. So, to answer your question regarding it being cyclical, I believe it is. That is, until they receive the tools in the form of therapy in order to properly deal with both their illness and the crazy things life throws at you.