I also have bpd and have had this exact fear forever. The reassurance from him is great and it’s good he continues to do that, but the real fear and anxiety around it goes away when you start to realize and feel reassured one or two things: if he falls for someone else, he was never mine, b/c someone who wants to spend their life with me would not be tempted like that; or he has proven over and over again he is loyal and dedicated to the relationship. Make a list of things he does, not just-