Whether we, or indeed she, like(s) it or not Katie WILL marry Andy. She WILL also infect him with a STD that she has, very kindly, had passed on to her from he whom she considers to be, I think, the love of her young life.
This will surely end one relationship and it is unlikely that a trusting relationship, with Robert, will ensue if, that is, Robert heeds his own advice passed on to his older sibling in last night’s episode re 18 being too young to settle down. Some do you know.
I also think (hope) that Robert says something to Andy (I don't consider his part is cast to be anything other that a braggart) but I also don't want the moment spoiled for when Katie is forced to tell Andy that she has cheated on him.
I am waiting for when Andy tells the blonde beauty to sling her hook, to see what Roberts response will be, after what he said to his brother and where she will turn when she finds she is both with child and a STD.