I don't see you having much of a relationship if you don't have trust. Would Little-Miss-Popularity like it if her boyfriend was hijacked at social gatherings for 'private talks and cuddles,' hmm? How come she has no BF of her own? Does she do this to other guys too is is it just your man? if it's the latter, then she has designs on him that means she wants a relationship with him, if it's all males then i suppose it's less for you to worry about, but while she's on the scene this is always going to be an issue for you. Quite frankly, your Bf's reaction 'i'll tell her not to cuddle me as you have insecurities' is very insensitive and he obviously enjoys the attention he gets from her. I think for your own peace of mind, I'd dump him. She'll either end up with him, or somebody who's jealous and less tolerant than you will end up slapping her!