Why he picks his lips?

I've been with my boyfriend for almost 7yrs. Before I actually decided to date him I was a little nervous, because his bottom lip is just really pink and I didn't know what was going on. Being good friends for a while I slowly learnt what the cause was. I noticed he picked his lips. He tried to hide it cause he was embarrassed about it, but I too use to bite at my bottom lip and stopped successfully on my own when I started noticing a little discoloration. I guess he been picking for about 30 yrs now. I ask him is he ever gonna stop and he gives me an excuse he don't have to cause it runs in his family. He put vaseline on Every night and day. But whats the point in that when he go right back to picking. Remind you that it's til he bleeding. He can be handing me something and I just so happen see blood on his fingers. Or he can talk to me and his lips start bleeding. I get so disgusted when I see it I get so upset to myself that he continues to hurt himself that way. I try to have understanding for I been there also. Its to the point where when he's sleep I just look at his lips and notice there's an indentation where a small part of lip is gone due to constant picking over the years. Everytime I ask him about it he always get upset even when I mean no harm, just to know what triggers it. So over 7 years I just deal with it in my own way until now I noticed that I'm slowly starting to pick back up the habitat which I definitely don't want to do and doing everything possible not to. Even if that means I have to end things. I just don't know how to deal with it anymore especially when he gets so upset when I try to talk to him about it. Him getting upset with me is the last way I feel that he should respond. I've given up romantically kissing, oral (which I can live without), seeing bloody fingers and lips, having to ask did you wash your hands all in years time. Just to make me feel like I'm doing wrong. I know I may have ranted a little to much or went to deep, but I'm at a lost of what to do cause I'm tired of seeing him do it Everyday hours at a time. I can't change him but should I feel guilty of not wanting to try anymore?