sex problems

Out of pure embarrassment I almost didn't post this but now I can't help but not. My boyfriend of over 3 years claims he has never gone down on a woman before and has only let me do it to him about a handful of times since we have been together and even then it's only for a couple seconds because he says it "tickles". I then find some flavored lube that I know was from before me because of the expiration date. Now my mind is running wild. He won't even play with me under my underwear it's always over the clothing which doesn't feel as good. He is 11 years older than me and always tells me he's past his prime. Makes me feel like maybe there is something wrong with me that makes him not even want to touch me there. I have pretty bad stretch marks from my 2 kids which he will also never touch and doesn't press to see me naked ever. What am I missing? Any advice??