Is this a normal brother and sister relationship?!

ChocolateLover
I have been dating this guy for nearly three years now and we have had quite a few problems but they always get sorted. The main problem that is not going away is how he is with his sister. As I am an only child I do not know what is normal brother and sister behavior. When we first started going out she was at university so it was never a problem but he would always say how attractive she was. Then one summer when we went on holiday he would constantly check her out and just stare at her bum all the time. He would even rearrange 'himself' after walking out the room. At first I thought this was just a coincidence and tried to forget about it because its his sister and only his sister but then I noticed this happened a lot and I started to feel really sick about it and I had to say something about it because I couldn't be near him and he said that it was disgusting that I thought he was checking out his sister...which is true...it really is disgusting but it was what he was doing! anyway after that he didn't seem to do it as much and nothing more was said about it. His sister has now returned home from university and he has started to do it again. The other day we were on webcam and his sister walked into the room with a very VERY short tight dress on and started posing for him and kept turning around to show him her bum and he sat there smiling with his chest out and his arms crossed just staring really disgusting and I just don't no what to do about it because I feel very very very sick about it but I don't feel I can say anything to him because it seems ridiculous. They are a year apart in age, he is older in his 20's and she is very fit and has a good figure but has no curves or anything. I am a normal girl not over weight but have curves but the way he looks at her makes me want to change the way I look because he obviously finds her very attractive. I am meant to be going on holiday with them this summer but really don't want to because of this situation...especially with her in her bikini. We had plans to go off and do things together on holiday as we haven't seen much of each other lately and he has now invited her along to all the things we have planned for just the two of us. Also since she has been back, the way he acts with me has changed a lot, he isn't as affectionate and he doesn't seem as interested. Am I being completely ridiculous? and what would you do? Thanks :D
Is this a normal brother and sister relationship?!
9 Opinion