Graham and Tina's friend, Xin are supposed to be getting married in Corrie, so how come they ain't kissed yet?

Has anyone else noticed this? I mean, they ain't a very believable couple if they don't snog, are they? (Even if they ARE only a sham couple!) What do you think? Or have they kissed, and I just missed it, and, if so, when? I'd really appreciate your angles on this one, please, guys. Much obliged! Peace and love! Be lucky! :)