It doesn't matter that much to me. I really like your writing, and I'll take it however you choose to, er, serve it to us.

I don't think it's at all unusual, even for men who love and are attracted to their partners, to look at pictures of other women. I do think it's disrespectful and inappropriate for him to be doing it in your presence, especially since you've voices your feelings.
All of this aside, please don't feel inadequate. You're not. You have every right to be treated with kindness and respect. If this relationship doesn't succeed for whatever reason, you will find love again. I'm not saying you should dump him over this, but don't settle for less than you deserve.

My "size range" expanded greatly over the years. As a teen, I only liked small BBWs, but that's changed. Now I'm attracted to pretty much any size, depending on the individual lady. I wouldn't draw a line in the sand and say a certain weight is the cutoff.