I do believe mine is caused by stress, which causes me to bite my lips and otherwise manipulate them in ways that cause them to peel. In my childhood I only bit the top middle part, and that was the only part affected, but I never thought much of it and would just bite it off again as soon as the skin came back.
I had some anxiety issues in college and got to the point where I just bit off as much of my lips as I could reach with my teeth, and again I would just keep doing that whenever I detected a piece of skin sticking off. Eventually I decided this made my lips look bad so I stopped biting them, and that's when I noticed the skin wouldn't heal normally. Then it became a sort of chicken/egg thing, where I wondered if the skin was messed up because I bit it, OR if I bit my lips because the skin was messed up but never realized it. I'm pretty sure the nervous lip-biting habit caused this though, and when I get stressed out I still tend to mess with my lips. And I believe it doesn't heal properly even when I do leave them alone because I messed with them for too long.
I was the one you're referring to that posted about the weather having no affect on the lip condition. I'm from Connecticut, which has hot, humid weather in the summer and cold winters. My lips were neither better nor worse in the winter or the summer. Coffee and tea do seem to make my lips worse, but only when they come into contact with them- if I drink iced coffee through a straw, my lips aren't affected.
For the record, my symptoms for the most part are just thickening/dying off of the skin and peeling. They don't bleed, and I get redness and burning occasionally. My entire lip isn't affected, only where the lips meet on the top and bottom. Outer regions look fine although they do get the occasional burning/redness thing for no known reason.