I agree mostly with
@Rodafina. She seems to be looking at this situation regarding the original poster and her boyfriend in a fair way. I mean to start there seems to be some overreaction here about the guy, and some will assume things or make harsh judgement way too prematurely.
I understand it can be hard sometimes to not take sides because of any black and white thinking tendencies, and to be patient and balanced if we are letting our own emotions, triggers or past bad experiences cloud our judgment, but let's relax, think things out calmly and objectively.
With regards to the facts, this is what is known:
--The boyfriend is Autistic; the partner/original poster is neurotypical
--The boyfriend seemed mostly very loving, committed and great for five years, from the information given.
--There was some big disagreement or conflict either once the original poster saw less affection from her boyfriend or after the boyfriend made it know he was no longer interested and committed.
--The boyfriend had a pattern of needing some relationships ended, but then he came back eventually, even in long time e!apsed.
--The original poster said the boyfriend knew manipulation well but showed it mostly for the last few months?
Regarding that last statement, how can we assume he was manipulating if for the first five years there was no mention of that from the original poster, with her suggesting he was fine then or had no issues with that then?
Manipulation, from my basic understanding of what that entails, often involves intent to deceive or sway someone from doing something using some intense emotion(s), action(s), words or distortion of the facts. I have not heard of any information here supporting that.
The boyfriend may have felt he was either incapable of proceeding further or severely wronged, as there could have been certain things happening in the relationship we were not hearing about here, as we are getting one side to things, and as lots of his thoughts and feelings could have been bottled up inside. Sometimes we do not express all our thoughts and feelings on the surface obviously.
Regard!ess, somehow he may have become overwhelmed over time or abruptly at the end by something, or felt he needed something different and could not lead on the op anymore. His mind could have been leaning in that direction much earlier, or snapped just towards the end. We may never know. He told her the truth and said he had to leave, then he did that. That is not manipulation.
From what I see he was not swaying her to do anything. Many Autistics in relationships, as seen in this forum so often, can bolt without stating in detail typical good reason and without working things out. That is not manipulation, but perhaps either low stress tolerance, severe stress if too much emotion becomes involved, confusion, black and white thinking, not wanting to lead one on further, or lack of shown empathy, by doing what is best for them or in not trying to work through emotional relationship issues.
So, whether ones likes the boyfriend or not, let us not assume anything harsh about the boyfriend's character and intent from this limited information , because if we do it calls more attention on us, when we have such negative judgement with limited information. None of us here are perfect in relationship attempts or in relationships , and staying in a relationship does not mean our character is better than those who left us.
Yes things do not look good for the relationship to resume anytime soon or to last, when there was a pattern of him doing such things before. Whether he could have been better or not there, who knows. Some things for some Autistics, they can not change. That is reality, not fiction. And so if he still has not come back in a few months, to explain things better or to say he was wrong for something, or to say he wants to try to work things out, after the apparent mostly five good years you had together, then I would say it is his next move there, but your option now to move on as well.
So from the facts or information given, I feel it is not fair to make a harsh judgement about who he is as a person and what his intent was, without getting specific balanced information and more details from the original poster, and as there could be several reasons why things ended we are not privy to, and as usually confrontation, strained or ended relationships involves two persons saying or doing hurtful things, even if one does more than the other. Usually it is instinct to want others to support us, or to b!ame just the other.
What is strange about this thread is that the original poster initially seemed very positive about the partner and mainly wanted to know if things could work out, but then seemed to want to agree with or please poster(s) who thought he was some manipulative person. Perhaps the op was afraid at first to say anything bad about her Autistic boyfriend when she came here, worrying she would offend us, but then when one or more seemed against him, she revealed more the truth.
I just hope the op though does not assume what one or more poster said is the truth. Look at all perspectives. We all have different unique views, triggers, life experiences and tolerances here. I hope one or more here are not putting pressure on you to tell you how to think or feel based on any of their fears or insecurities. I just know certain things some Autistics say or do in or regarding relationships, others do not do. Some Autistics can manipulate, but I would bet the majority do not. Their abrupt decisions and sensitivities are often not with intent to often manipulate, hurt or sway. Facts and black and white thinking may drive them more, and avoidance of real close connections or people when conflict and stress mounts.