I SO understand what you are saying. Here's a couple of quick examples why:

-The yearly class photo was one of the worse things about teaching school for me, to the point that when I quit, one of the first things I thought was that now I don't have to do the pix thing. when I see those pix now, I feel like I am looking at someone else.

-I HATE the way I look. And now I am old, and I think- wow- you looked better young, why didn't you think that way then since it's a lost cause now.

-I HATE mirrors, and I can tell you ones that are better than others for the 20 mile radius I am in.

-When any event comes up where there might be photos, I start to panic ahead of time and avoid the camera at all costs. If I do up having to see a photo later, I get sick about it and want to steal the pix and destroy it!

-We have also had arguments about this at family gatherings. I get the "oh just do it", and "When you argue you just make it worse." It's insulting. I think, for the most part, they are getting it, but it is still an issue.( But how would they like it if I put one of their issues in their faces?")

-Renewing my drivers license makes me sick to my stomach. It was awful last time, and I am already dreading the next. My pix is downright scary and SOOOO depressing.

- And finally, I have actually had many discussions with my husband in case of my death. No picture in the paper obituary. No service with photos around. No. No. That is not who I am/was. The only pix I like of myself are when I was really young and naive and cute.

So I am sorry to digress with my own stuff. You have told someone how you feel, and they are ignoring that. Id like to give him the benefit of the doubt, and say he's just clueless since he doesn't feel this way. BUT it's not right that he really isn't listening to you. In my case, the dread would build up and up. I guess I'd get through it, but you don't have to even do that. So what if you don't? You don't need to say yes because this guy thinks he can help you by doing it. YOu don't need to be his personal cause.
Say no if you don't want to, and then don't think about it. Maybe someday you will welcome photos, but if not. oh well... In the scheme of things, you don't need to add this to your worries. It just doesn't matter, if you know what I mean. And you have nothing to apologize for, in my opinion.

PS BTW, as a side note.. my daughter LOVES having her picture taken- always has. SHes almost 21 now, and even when she was little she would stand in front of her brother sometime. He, on the other hand, still hates to have his pix taken, but that's another story .....