I feel like my boyfriend is too attractive for me?

Hey guys! Lately I've been feeling kinda down and insecure around my boyfriend because I feel like I'm not attractive enough for our relationship. We're long distance for now and I can't help but feel like I'm not pretty enough to hold his interest while he's away. He mentioned a friend today and was very complimentary of her (calling her "a doll" and saying she was "very pretty") and once I saw a picture of her I was floored: she was beautiful, which only added to my anxiety. He constantly tells me he loves me and we have even discussed such insecurities but I can't help but feel as if I'm not pretty enough for him. Help?