What is your opinion on this guy?

Okay so I'll try and put this in short...My sister's boyfriend is really peeing me off and I wondered if it wasn't just me. Recently, me and my bf have been cohabiting with them which is getting along fine...except with him. He separates all of our stuff because he's worried we might eat their food or whatever, hes moaned at me and my bf for leaving washing up on the side (yet he does it now anyway) and every time I walk into a room, he walks out. He doesn't like my (and my sister's) 2 brothers, or my (and my sister's) dad or any of my sister's friends but won't admit it to them because he doesn't want to be seen as horrid (although he's told us he doesn't like them). Oh and he doesn't like my cat??? :/ They both have a cat and recently, me and my bf wanted to get another kitten so that we all have one each and so that my cat has a companion. However, hes disliking the idea because he says that 'four is too many cats in a house'. Well, it isn't because its a THREE bedroom house, pretty large and we look after our own cat anyway. I reckon he just doesn't want us getting another cat because he's worried it will start using HIS cats litter trays and eat their food which is petty because whenever we catch out cat doing that, we move him. His excuse for us not getting a kitten is that 'they'd already decided on getting their two kittens so we don't have a lot of choice in the matter'. My sister is fine with me about everything and sometimes I feel she has to moan at us because he hasn't got the balls to do it on occasion. So...what do you guys think? I am seriously not exaggerating this, this is what he's truly like. What's your honest opinion?