Can Someone Help Me Here?

were lesbians and weve been going out for a littleeee over 8 months and everything is still really really great and everything but since the beginning of the relationship to now she has put on a little bit of weight. i absolutly have no problem with it i think shes the most ABSOLUTE beautiful girl in the world and that i have ever seen and i tell her every day that she is beautiful. and i dont just say it to make her feel good, i truly think so. i didnt know that it was bothering her but she doesnt let me touch her stomach anymore or anything and she feels really really insecure and fat and she says she feels gross alot. it makes me SOO sad to know she feels like this. shes the type of person that LOOKS like she has alot of confidence and is really happy you know what i mean? but ive come to see that shes not, shes happy with our relationship and everything we love eachother VERY very much but i dont know how to make her see that shes so so beautiful inside and out. she knows I think so, which im happy about, but she doesnt think shes attractive at all. she doesnt like to have sex AS much either. we used to do it allllll the time and we still do, but shes just self concious and everything and i used to LOVE that she was the type of person that didnt care about her apperance or of what people thought of her, but now she does. what can i do? thank you very much :)