Your relationship sounds like it had the same progression my relationship with my daddy went, just with the genders flipped, but its a lot of the same issues. When he gave me the go-ahead that he would start putting me in diapers, I took advantage of this like it sounds your boyfriend is. This was because he was the first and still only person that ever did this for me and that I've ever trusted to do this for me since becoming of age. Now I can't speak for why your boyfriend is becoming so addicted to diaper play, since he says he had two girlfriends that did this for him, messy diapers included, no questions asked, but I really don't buy it. Where are these magically accepting ex-girlfriends and why did they break up if they had absolutely no problem with indulging his fantasies? But that's another issue, and there's more here it seems than calling your boyfriend out on his BS.