uklad, I think NeverEverEnds explained this in his/her post, but I would guess the skin is hard to get off because you don't put anything on it to keep it soft. Certain things you apply will make peeling easier or more difficult, some will speed it up and some will slow it down. I know from my experience that when I tried not putting stuff on my lips for several days, the skin stayed firmly on even though there were layers of it building up on my lips. Trying to peel it would hurt because it was bound to the skin underneath. If you'd tried any products that you felt made the skin come off more often, like maybe Aquaphor or Blistex, those have the opposite effect.
I haven't tried the Wheatgrass cream but it sounds soothing so I might. Blistex seems a bit harsh for this. I do like the Aquaphor though, and it's good to use during the day if I'm at work and don't feel comfortable doing the peeling thing even though my lips are starting to look funny. It masks it pretty well. Might be more difficult for a guy to get away with though because of the gloss factor.
To people who've used the Wheatgrass cream: Does it make your lips look shiny?