Casey has every right to be annoyed.
This bloke said he liked her, wanted to see how things go on the outside and said he wanted to go on holiday with her. He was gropping and kissing her all while he said this too.
The next day he kisses Jasmine and doesn't even have the bottle to be straight with Casey. He just skirts around the subject and even when Casey asked him straight out to be honest with her, he couldn't do it.
In fact the next day he was kissing Casey again.
He sent her all these mixed messages and lost his balls. If he liked Yasmin, fine. I doubt this is the issue with Casey. The issue is that he just couldn't be honest enough to tell her that and strung her along for as long as possible.
It's all blown up his face because of HIS actions, not Casey's or Yasmine's for that matter. He's responsible for his own mess.