Long message incoming, sorry! 
I'm kind of... Yeah, I'll have to disagree on this, sorry. I mean, it could be unconscious (very, veryyy unconscious then) but i really do want commitment and I don't fear it. The thing is, I refuse to accept anybody as a partner. I don't think I ask for too much, that my standards are too high but it always have been difficult for me to be both physically and emotionnaly attracted by someone and yeah, when I am, it doesn't work out. This is also why I end up being very disappointed when it ends. The men I've met so far were truly looking for commitment, they were not unavailable (one of them got married a year after our breakup so I think he was pretty available) but between us, didn't work out.
Plus, I've never had any family difficulties nor have I suffer from abuse / trauma but I don't know, it just does not work out. Probably because of the way I communicate, I tend to close myself off when something goes wrong and when I'm ready to talk, it's already too late for the other person.
You said it could stem from chilhood and I've always been spoiled by my parents so maybe, if I don't get the things I want, the way I want them, I shut myself off, which leads to a breakup 
I know I've never had any very long relationship but I do know what it takes to be in a serious commited relatioship: I do know there are ups and downs and I've always been ready to live them, I don't live in a fantasy world but I've also always been the only one putting in the effort.
So indeed, deep down I do really yearn for a close, loving bond with someone and a safe secure home life. And I already see relationships as a process of ups and downs, entailing learning, maturation, and [above all] mutual support. It has always been the way I see love and relationships. But still, it does not work. And I'm sorry to say that but I'm not looking for a challenge or a training. I don't want to lie to myself by making a deception a training or a way to improve myself. A deception remains a deception. A relationship that doesn't work out remains a failure. I mean, I can learn from it, keep good memories about it but still, it failed. I won't say it is always the "same old, same old" but in the end, I am still single. I've learned a lesson in the process, great but still, I'm single. And it is not what I'm aiming for.
It is the same thing when you have to play a game: you go to win hopefully, not only to participate, right? This is the way I view things on love: I might get a million lessons but if in the end, I haven't found my person, what's the point?
Now, you are absolutly right about the fact I do need a calmer centre to control [my] tendency to emotional extremes. I do tend to shut myself off when something doesn't work out the way I wanted it. It's always after I close myself off they run away. No discussion possible, no trying to understand why, they just don't want to talk things out. I think i was too much of an annoyance.
I guess my question should have been more about will I meet someone who will try to understand me, put in the effort, be patient as any normal true partner would. As I would actually.
You are also right about the fact that I sometimes am aloof, or seem to be more precisely. I'm pretty shy and people often tell me I seemed not interested or in my head when they first met me. So you're right, it is definitely an obstacle I have to work hard on.
Thanks for your help and I am sorry if my message sounded agressive. English isn't my native language and it sounded agressive to me whereas it was not at all my intention.