How about I give my sister my girlfriend's necklace and then get mad when she demands to have it back?
Why do you want to set her up like this and then get angry?
I know the necklace was expensive and gives me a good excuse to annoy her.
It is petty to set up your sister like this. It is not right to be angry with your siblings because of petty things.
I thought you had to have a glimmer of hope in order to live and here you are being all negative.
You should really try not to treat this like a game. It's wrong to get angry with your siblings over petty things. I would try to be nicer to your girlfriend and your sister so they can all get along.