Thats not correct about AK and RG. RG 'fancied' AK and told the boys downstairs so. It is also likely AK knew about this infatuation. IMO RG's 'stories' about meeting Meredith are just that... stories to put himself in the best possible light since he knew there was evidence of himself at the cottage. According to all the witnesses presented, Meredith did not meet or talk to RG on Halloween.
There would have been no reason for RG to innocently want to use the bathroom at the cottage with almost everything within 5-10 minutes walking distance. If he did so, he would have had to already have a plan of assaulting Meredith. Plus IMO, what is the probability of Meredith opening the door for a virtual stranger to use the bathroom, then having some kind of relations with them AFTER using they take a dump in the bathroom? What a instant turn off. If that was the 'plan'... it was a crappy one. Pardon the pun.