My boyfriend is ashamed to be seen with me?

we've been together for 9 months and he's always been reluctant to hold my hand when we are out in public. sometimes to the extreme that he wouldn't even talk to me when he's with his friends, or lie to other people that I'm just a "friend". I asked him why he's doing this, I forced it out of him and he said because he's really shallow, he says I'm not pretty or skinny enough for his standards and he's afraid of what people will think when they find out I'm his girlfriend. then I hinted that I'm gonna leave him but he begged me not to go, he says he really loves me and he's changing, and I did notice that he is slowing improving. he's only average looking and he's really skinny, I don't know how pretty of a girl he wants. should I wait for him to change or just leave it and I too should feel embarrassed by him and hide our relationship?
My boyfriend is ashamed to be seen with me?
Post Opinion