While Rob Kardashian has been busy spending time with girlfriend Blac Chyna, his sister Khloe is simply missing him. On Thursday night, Khloe took to Instagram to let Rob know how she feels about him and based on her choice of emoji, she seems to be really sad. Alongside a picture of Rob planting a kiss on Khloe?s cheek, she sent a message to her brother with the caption, ?It?s simple. I miss you